Synlett 2013; 24(1): 114-116
DOI: 10.1055/s-0032-1317695
letter
© Georg Thieme Verlag Stuttgart · New York

An Improved, Fully Heterogeneous, Diastereoselective Synthesis of (Z)-α-Bromonitroalkenes

Alessandro Palmieri
Green Chemistry Group, School of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino (MC), Italy   Fax: +39(0737)402297   Email: roberto.ballini@unicam.it
,
Serena Gabrielli
Green Chemistry Group, School of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino (MC), Italy   Fax: +39(0737)402297   Email: roberto.ballini@unicam.it
,
Roberto Ballini*
Green Chemistry Group, School of Science and Technology, Chemistry Division, University of Camerino, Via S. Agostino 1, 62032 Camerino (MC), Italy   Fax: +39(0737)402297   Email: roberto.ballini@unicam.it
› Author Affiliations
Further Information

Publication History

Received: 30 October 2012

Accepted: 02 November 2012

Publication Date:
28 November 2012 (online)

 


Abstract

α-Bromonitroalkenes are both key starting materials for the preparation of complex structures and possess antimicrobial activity. In this context, we disclose a simple, fully heterogeneous synthetic approach for their preparation in good overall yields.


#

Unsaturated nitro compounds are an important class of valuable precursors to a wide variety of target molecules.[ 1 ] The utility of conjugated nitroalkenes in organic synthesis is largely due to their versatile reactivity as Michael acceptors, dipolarophiles, 1,3-dipoles, dienophiles, and heterodienes.[ 2 ] Nitroalkenes are also distinguished by their diverse biological activities.[ 3 ] In this respect, of particular interest are the α-bromonitroalkenes 5 since they have shown important antimicrobial activities[ 4 ] as well as being key intermediates.[ 5 ]

Due to the importance of these compounds, their easy availability is strategically important and simpler synthetic procedures for their preparation would increase the importance of these bifunctionalized alkenes. The general synthetic method for the preparation of α-bromonitroalkenes involves bromination–debromination of nitroalkenes 3 (Scheme [1]). However, since nitroalkanes 3 are generated by Henry reaction followed by elimination, it is clear that the preparation of α-bromonitroalkenes 5 starting from their ultimate precursors (nitromethane and aldehydes) involves a complex multistep sequence.[ 6 ]

Zoom Image
Scheme 1

Some decades ago, a direct procedure[ 7 ] involving the nitroaldol condensation of aldehydes with bromonitromethane in the presence of tri-n-butylarsine was described. However, the method appears to work just with aromatic aldehydes, and requires a large excess of bromonitromethane, a dry atmosphere, and high temperatures. Moreover, the reaction must be manipulated with attention in order to avoid possible explosion, probably due to the use of tri-n-butylarsine. Thus, a simpler method would be valuable. In this context, based on our previous experience in the nitroaldol (Henry) reaction,[ 8 ] we have developed a new, simple, mild, and fully heterogeneous approach for the synthesis of α-bromonitroalkenes 5 starting from the Henry reaction between aldehydes 1 and bromonitromethane 6, followed by the dehydration of the obtained crude nitro alcohols (Scheme [2]).

We chose, as a model system, the reaction of 6 with hexanal (1a) under basic and solvent-free conditions (carbonate on silica), in which the crude nitroalkanol 7a can be directly dehydrated, by Amberlyst 15/Ac2O[ 9 ] into the target compound 5a avoiding any intermediate purification step.

Zoom Image
Scheme 2 Reagents and conditions: a) SolFC, carbonate on silica, r.t., 4.5 h; b) Amberlyst 15, EtOAc, r.t., 1.5 h.

As reported in Table [1], the optimal result was obtained by employing 0.3 equivalents of carbonate on silica, coupled with 500 mg/mmol of Amberlyst 15 and three equivalents of Ac2O.

Table 1

Entry

Carbonate on silica (equiv)

Amberlyst 15 (g/mmol)

Ac2O (equiv)

Yield of 5a (%)a

 1

0.1

0.25

2

20

 2

0.1

0.35

2

31

 3

0.1

0.5

2

48

 4

0.1

1.0

2

50

 5

0.1

0.5

3

56

 6

0.1

0.5

4

54

 7

0.2

0.5

3

67

 8

0.3

0.5

3

82

 9

0.4

0.5

3

81

10

0.3

3

no product

11

0.3

0.5

no product

a Yield of pure isolated product.

In order to assess the generality of our procedure we investigated a variety of substrates and, as reported in Table [2], satisfactory to good yields (55–85%) were achieved with aromatic and aliphatic aldehydes, including functionalized substrates.[ 10 ] Only 5-bromo-2-furfural 1k (Table [2], entry 11) afforded a low yield (31%) of alkene 5k, probably due to the chemical frailty of the furan ring.

Furthermore, all the obtained α-bromonitroalkenes were isolated as a single Z-diastereomer. The configuration was established by comparison with the literature data.[4d] [6c]

Table 2

Entry

R

Time (h)

Yield of 5 (%)a

 1

1a Me(CH2)4

4.5

5a 82

 2

1b Me(CH2)6

5

5b 82

 3

1c cyclohexyl

5

5c 84

 4

1d Ph(CH2)2

4

5d 85

 5

1e EtOOC

5

5e 61

 6

1f 4-t-BuC6H4

6

5f 72

 7

1g 3-MeOC6H4

5

5g 73

 8

1h 4-MeOC6H4

5

5h 55

 9

1i 2-BrC6H4

5

5i 72

10

1j 3,4,5-(MeO)3C6H2

6

5j 56

11

1k 5-Br-2-furyl

5

5k 31

a Yield of pure isolated product.

In conclusion, our procedure offers important advantages with respect to the previous reported approaches since it gives access to the target compounds, without the need for excess bromonitromethane, under mild reaction conditions (room temperature) and short reaction times, with evident economical and environmental benefits. Moreover, a variety of other important functionalities can be tolerated giving access to polyfunctionalized α-bromonitroalkenes that could be of interest as targets with potential biological activities.[ 4 ]

Finally, it is important to point out that our method employs a fully heterogeneous procedure and that the final dehydration of nitroalkanol proceeds under acidic conditions, contrary to the standard procedures that usually employ basic conditions.


#

Acknowledgment

The authors thank the University of Camerino and MIUR, Italy (FIRB National Project ‘Metodologie di nuova generazione nella formazione di legami carbonio-carbonio e carbonio-eteroatomo in condizioni eco-sostenibili’) for financial support.

  • References and Notes

    • 1a Perekalin VV, Lipina ES, Berestovitskaya VM, Efremov DA In Nitroalkenes Conjugated Nitro Compounds . Wiley; Chichester: 1994
    • 1b Ballini R In Studies in Natural Products Chemistry . Atta-ur-Rahman Elsevier; Amsterdam: 1997: 117
    • 1c Ballini R, Marcantoni E, Petrini M In Amino Group Chemistry . Ricci A. Wiley-VCH; Weinheim: 2008: 93
    • 1d Ballini R, Gabrielli S, Palmieri A. Curr. Org. Chem. 2010; 14: 65

      See, for example:
    • 2a Berner OM, Tedeschi L, Enders D. Eur. J. Org. Chem. 2002; 1877
    • 2b Krause N, Hoffmann-Röder A. Synthesis 2001; 171
    • 2c Denmark SE, Thorarensen A. Chem. Rev. 1996; 96: 137
    • 2d Tietze LF, Kettschau G. Top. Curr. Chem. 1997; 189: 1
    • 2e Namboothiri IN. N, Hassner A. Top. Curr. Chem. 2001; 216: 1
    • 3a Kabalka GW, Varma RS. Org. Prep. Proced. Int. 1987; 19: 283
    • 3b Barret AG. M. Chem. Soc. Rev. 1991; 20: 95
    • 3c Blades K, Butt AH, Cockerill GS, Easterfield HJ, Lequeux TP, Percy JM. J. Chem. Soc., Perkin Trans. 1 1999; 3609
    • 3d Hoashi Y, Yabuta T, Takemoto Y. Tetrahedron Lett. 2004; 45: 9185
    • 3e Dadwal M, Mohan R, Panda D, Mobin SM, Namboothiri IN. N. Chem. Commun. 2006; 338
    • 3f Rastogi N, Mohan R, Panda D, Mobin SM, Namboothiru IN. N. Org. Biomol. Chem. 2006; 4: 3211
    • 3g Mohan R, Rastogi N, Namboothiri IN. N, Mobin SM, Panda D. Bioorg. Med. Chem. 2006; 14: 8073
    • 3h Parry R, Nishino S, Spain J. Nat. Prod. Rep. 2011; 28: 152

      See, for example:
    • 4a Cancio C, Ramon N, Placeres G, Exiquio T. WO 0153283, 2001
    • 4b McCoy WF, Thornburgh S. WO 8911793, 1989
    • 4c González-Diaz H, Tenorio E, Castañedo N, Santana L, Uriarte E. Bioorg. Med. Chem. 2005; 13: 1523
    • 4d Estrada E, Gόmez M, Castañedo N, Pérez C. J. Mol. Struct. (Theochem) 1999; 468: 193
    • 5a Ganesh M, Namboothiri IN. N. Tetrahedron 2007; 63: 11973
    • 5b McCooey SH, McCabe T, Connon SJ. J. Org. Chem. 2006; 71: 7494
    • 5c Romashov LV, Khomutova YA, Danilenko VM, Ioffe SL, Lesiv AV. Synthesis 2010; 407

      See, for example:
    • 6a Sarkisyan ZM, Sadikov KD, Smirnov AS, Kuzhaeva AA, Makarenko SV, Anisimova NA, Deiko LI, Berestovitskaya VM, Russian VM. J. Org. Chem. 2004; 40: 908
    • 6b Tuan DT, Tung DT, Langer P. Synlett 2006; 2812
    • 6c Ganesh M, Namboothiri IN. N. Tetrahedron 2007; 63: 11973
  • 7 Shen Y, Yang B. Synth. Commun. 1993; 23: 1
    • 8a Ballini R, Castagnani R, Petrini M. J. Org. Chem. 1992; 57: 2160
    • 8b Ballini R, Bosica G, Forconi P. Tetrahedron 1996; 52: 1677
    • 8c Ballini R, Bosica G. J. Org. Chem. 1997; 62: 425
    • 8d Ballini R, Bosica G, Parrini M. Chem. Lett. 1999; 1105
    • 8e Ballini R, Bigi F, Giorgi E, Maggi R, Sartori G. J. Catal. 2000; 191: 348
    • 8f Ballini R, Bosica G, Livi D, Palmieri A, Maggi R, Sartori G. Tetrahedron Lett. 2003; 44: 2271
    • 8g Ballini R, Fiorini D, Gil MV, Palmieri A. Tetrahedron 2004; 60: 2799
    • 8h Ballini R, Barboni L, Palmieri A. Synlett 2007; 3019
    • 8i Ballini R, Bosica G, Palmieri A, Pizzo F, Vaccaro L. Green Chem. 2008; 10: 541
    • 8j Ballini R, Noé M, Perosa A, Selva M. J. Org. Chem. 2008; 73: 8520
  • 9 Usually, the dehydration of bromonitroalkanols is performed under basic conditions, see ref. 6.
  • 10 Typical Procedure for the Synthesis of Compounds 5 The catalyst (0.56 g, 0.3 mmol) was slowly added at r.t. to a mechanically stirred mixture of the bromonitromethane (6, 1 mmol, 0.155 g, pure 90%) and the requisite aldehyde 1 (1 mmol), and the reaction was stirred for the appropriate time (see Table). The mixture was then treated with EtOAc (5 mL), and the catalyst was filtered off and washed with additional EtOAc (10 mL). The solution was concentrated under reduced pressure to a volume of 3 mL and then treated with Ac2O (306 mg, 3 mmol) and Amberlyst 15 (0.5 g) and stirred, at r.t., for an additional 1.5 h. Finally, the Amberlyst 15 was removed by filtration, washing with EtOAc (7 mL), and the solution was concentrated under vacuum giving the crude product 5 which was purified by flash chromatography (hexane–EtOAc = 9:1). (Z)-1-Bromo-1-nitrohept-1-ene (5a) Light yellow oil. IR (neat): ν = 3045, 1551, 1325, 1261, 942, 722 cm–1. 1H NMR (400 MHz, CDCl3): δ = 0.91 (t, 3 H, J = 6.8 Hz), 1.30–1.40 (m, 4 H), 1.51–1.61 (m, 2 H), 2.37 (q, 2 H, J = 7.3 Hz), 7.67 (t, 1 H, J = 7.3 Hz). 13C NMR (100MHz, CDCl3): δ = 14.1, 22.5, 27.3, 31.3, 31.6, 131.2, 141.6. MS (EI, 70 eV): m/z (%) = 165, 142, 119, 95, 69, 55, 41 (100), 39, 30. Anal. Calcd for C7H12BrNO2 (222.08): C, 37.86; H, 5.45; N, 6.31. Found: C, 37.91; H, 5.49; N, 6.28. (Z)-1-Bromo-1-nitronon-1-ene (5b) Light yellow oil. IR (neat): ν = 3040, 1542, 1321, 1254, 960, 768 cm–1. 1H NMR (400 MHz, CDCl3): δ = 0.89 (t, 3 H, J = 6.8 Hz), 1.23–1.41 (m, 8 H), 1.50–1.61 (m, 2 H), 2.37 (q, 2 H, J = 7.3 Hz), 7.66 (t, 1 H, J = 7.3 Hz). 13C NMR (100 MHz, CDCl3): δ = 14.3, 22.8, 27.6, 29.1, 29.4, 31.3, 31.9, 131.2, 141.6. MS (EI, 70 eV): m/z (%) = 234, 121, 93, 81, 67, 55, 43 (100), 41, 39, 29. Anal. Calcd for C9H16BrNO2 (250.13): C, 43.22; H, 6.45; N, 5.60. Found: C, 43.27; H, 6.49; N, 5.58. (Z)-(2-Bromo-2-nitrovinyl)cyclohexane (5c) Light yellow oil. IR (neat): ν = 3030, 1539, 1320, 971, 960, 761 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.18–1.44 (m, 6 H), 1.65–1.84 (m, 4 H), 2.39–2.53 (m, 1 H), 7.48 (d, 1 H, J = 9.8 Hz). 13C NMR (100 MHz, CDCl3): δ = 25.3, 25.7, 30.8, 40.8, 129.7, 145.3. MS (EI, 70 eV): m/z (%) = 218, 216, 137, 119, 97, 91, 81, 79, 71, 69, 55 (100), 41, 39. Anal. Calcd for C8H12BrNO2 (234.09): C, 41.05; H, 5.17; N, 5.98. Found: C, 41.09; H, 5.21; N, 5.96. (Z)-(4-Bromo-4-nitrobut-3-enyl)benzene (5d) Light yellow oil. IR (neat): ν = 3035, 1618, 1525, 1331, 937, 750, 724, 698 cm–1. 1H NMR (400 MHz, CDCl3): δ = 2.71 (q, 2 H, J = 7.7 Hz), 2.88 (t, 2 H, J = 7.7 Hz), 7.17–7.36 (m, 5 H), 7.67 (t, 1 H, J = 7.7 Hz). 13C NMR (100 MHz, CDCl3): δ = 33.0, 33.6, 127.0, 128.5, 129.0, 131.8, 139.7, 140.2. MS (EI, 70 eV): m/z (%) = 240, 238, 129, 91 (100), 65. Anal. Calcd for C10H10BrNO2 (256.10): C, 46.90; H, 3.94; N, 5.47. Found: C, 46.88; H, 3.97; N, 5.44. (Z)-Ethyl 3-Bromo-3-nitroacrylate (5e) Light yellow oil. IR (neat): ν = 1733, 1622, 1552, 1323 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.35 (t, 3 H, J = 7.3 Hz), 4.34 (q, 2 H, J = 7.3 Hz), 7.74 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 14.2, 62.8, 125.8, 139.3, 162.2. MS (EI, 70 eV): m/z (%) = 180, 178, 166, 164, 151, 149, 133, 131, 106, 104, 69, 53, 29 (100). Anal. Calcd for C5H6BrNO4 (224.01): C, 26.81; H, 2.70; N, 6.25. Found: C, 26.86; H, 2.72; N, 6.22. (Z)-1-(2-Bromo-2-nitrovinyl)-4-tert-butylbenzene (5f) Yellow solid, mp 50–52 °C. IR (neat): ν = 3030, 1599, 1530, 1325, 953, 834, 762 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.35 (s, 9 H), 7.51 (d, 2 H, J = 8.5 Hz), 7.86 (d, 2 H, J = 8.5 Hz), 8.64 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 31.3, 35.4, 126.3, 127.3, 127.5, 131.3, 136.7, 156.3. MS (EI, 70 eV): m/z (%) = 285, 283, 270, 268, 222, 220, 143 (100), 128, 115, 57. Anal. Calcd for C12H14BrNO2 (284.15): C, 50.72; H, 4.97; N, 4.93. Found: C, 50.76; H, 5.00; N, 4.90. (Z)-1-(2-Bromo-2-nitrovinyl)-3-methoxybenzene (5g) Yellow solid, mp 68–70 °C. IR (neat): ν = 3070, 3029, 1607, 1553, 1331, 1176, 897, 743 cm–1. 1H NMR (400 MHz, CDCl3): δ = 3.86 (s, 3 H), 7.07 (d, 1 H, J = 7.7 Hz), 7.38–7.46 (m, 3 H), 8.61 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 55.6, 115.8, 118.0, 124.0, 128.5, 130.2, 131.5, 136.6, 159.9. MS (EI, 70 eV): m/z (%) = 259, 257, 212, 210, 150, 148, 132 (100), 102, 89, 77, 63. Anal. Calcd for C9H8BrNO3 (258.07): C, 41.89; H, 3.12; N, 5.43. Found: C, 41.93; H, 3.10; N, 5.40. (Z)-1-(2-Bromo-2-nitrovinyl)-4-methoxybenzene (5h) Yellow solid, mp 59–61 °C. IR (neat): ν = 3041, 1520, 1310, 1261, 1181, 957, 825 cm–1. 1H NMR (400 MHz, CDCl3): δ = 3.88 (s, 3 H), 7.00 (d, 2 H, J = 8.5 Hz), 7.92 (d, 2 H, J = 8.5 Hz), 8.63 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 55.8, 114.8, 122.6, 125.6, 133.7, 136.6, 163.0. MS (EI, 70 eV): m/z (%) = 259, 257, 212, 210, 132 (100), 117, 89, 63. Anal. Calcd for C9H8BrNO3 (258.07): C, 41.89; H, 3.12; N, 5.43. Found: C, 41.93; H, 3.09; N, 5.45. (Z)-1-Bromo-2-(2-bromo-2-nitrovinyl)benzene (5i) Yellow waxy solid. IR (neat): ν = 3078, 3035, 1606, 1582, 1532, 1300, 898, 764, 733, 703 cm–1. 1H NMR (400 MHz, CDCl3): δ = 7.35 (t, 1 H, J = 7.7 Hz), 7.44 (t, 1 H, J = 7.7 Hz), 7.69 (d, 1 H, J = 7.7 Hz), 7.86 (d, 1 H, J = 7.7 Hz), 8.77 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 125.7, 127.7, 130.6, 131.3, 131.6, 132.5, 133.5, 136.2. MS (EI, 70 eV): m/z (%) = 309, 307, 305, 262, 260, 258, 228, 226, 198, 196, 182, 180 (100), 147, 101, 75, 50. Anal. Calcd for C8H5Br2NO2 (306.94): C, 31.30; H, 1.64; N, 4.56. Found: C, 31.33; H, 1.65; N, 4.54. (Z)-5-(2-Bromo-2-nitrovinyl)-1,2,3-trimethoxybenzene (5j) Orange solid, mp 113–115 °C. IR (neat): ν = 3075, 3035, 1603, 1577, 1522, 1333, 1246, 1125, 824, 618 cm–1. 1H NMR (400 MHz, CDCl3): δ = 3.91 (s, 6 H), 3.93 (s, 3 H), 7.19 (s, 2 H), 8.59 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 56.4, 56.5, 61.3, 105.9, 108.9, 125.2, 127.1, 131.9, 136.7, 141.8, 153.4. MS (EI, 70 eV): m/z (%) = 319, 317, 272, 270, 257, 255, 192, 177 (100), 149, 134, 119, 63. Anal. Calcd for C11H12BrNO5 (318.12): C, 41.53; H, 3.80; N, 4.40. Found: C, 41.57; H, 3.82; N, 4.38. (Z)-2-Bromo-5-(2-bromo-2-nitrovinyl)furan (5k) Yellow solid, mp 87–89 °C. IR (neat): ν = 3134, 3036, 1618, 1537, 1505, 1348, 1292, 1025, 948, 818, 786, 645 cm–1. 1H NMR (400 MHz, CDCl3): δ = 6.61 (d, 1 H, J = 3.4 Hz), 7.37 (d, 1 H, J = 3.4 Hz), 8.50 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 115.8, 122.3, 124.0, 125.1, 129.6, 148.6. MS (EI, 70 eV): m/z (%) = 299, 297, 295, 225, 223, 221, 135, 133, 79, 63 (100). Anal. Calcd for C6H3Br2NO3 (296.90): C, 24.27; H, 1.02; N, 4.72. Found: C, 24.30; H, 1.03; N, 4.69.

  • References and Notes

    • 1a Perekalin VV, Lipina ES, Berestovitskaya VM, Efremov DA In Nitroalkenes Conjugated Nitro Compounds . Wiley; Chichester: 1994
    • 1b Ballini R In Studies in Natural Products Chemistry . Atta-ur-Rahman Elsevier; Amsterdam: 1997: 117
    • 1c Ballini R, Marcantoni E, Petrini M In Amino Group Chemistry . Ricci A. Wiley-VCH; Weinheim: 2008: 93
    • 1d Ballini R, Gabrielli S, Palmieri A. Curr. Org. Chem. 2010; 14: 65

      See, for example:
    • 2a Berner OM, Tedeschi L, Enders D. Eur. J. Org. Chem. 2002; 1877
    • 2b Krause N, Hoffmann-Röder A. Synthesis 2001; 171
    • 2c Denmark SE, Thorarensen A. Chem. Rev. 1996; 96: 137
    • 2d Tietze LF, Kettschau G. Top. Curr. Chem. 1997; 189: 1
    • 2e Namboothiri IN. N, Hassner A. Top. Curr. Chem. 2001; 216: 1
    • 3a Kabalka GW, Varma RS. Org. Prep. Proced. Int. 1987; 19: 283
    • 3b Barret AG. M. Chem. Soc. Rev. 1991; 20: 95
    • 3c Blades K, Butt AH, Cockerill GS, Easterfield HJ, Lequeux TP, Percy JM. J. Chem. Soc., Perkin Trans. 1 1999; 3609
    • 3d Hoashi Y, Yabuta T, Takemoto Y. Tetrahedron Lett. 2004; 45: 9185
    • 3e Dadwal M, Mohan R, Panda D, Mobin SM, Namboothiri IN. N. Chem. Commun. 2006; 338
    • 3f Rastogi N, Mohan R, Panda D, Mobin SM, Namboothiru IN. N. Org. Biomol. Chem. 2006; 4: 3211
    • 3g Mohan R, Rastogi N, Namboothiri IN. N, Mobin SM, Panda D. Bioorg. Med. Chem. 2006; 14: 8073
    • 3h Parry R, Nishino S, Spain J. Nat. Prod. Rep. 2011; 28: 152

      See, for example:
    • 4a Cancio C, Ramon N, Placeres G, Exiquio T. WO 0153283, 2001
    • 4b McCoy WF, Thornburgh S. WO 8911793, 1989
    • 4c González-Diaz H, Tenorio E, Castañedo N, Santana L, Uriarte E. Bioorg. Med. Chem. 2005; 13: 1523
    • 4d Estrada E, Gόmez M, Castañedo N, Pérez C. J. Mol. Struct. (Theochem) 1999; 468: 193
    • 5a Ganesh M, Namboothiri IN. N. Tetrahedron 2007; 63: 11973
    • 5b McCooey SH, McCabe T, Connon SJ. J. Org. Chem. 2006; 71: 7494
    • 5c Romashov LV, Khomutova YA, Danilenko VM, Ioffe SL, Lesiv AV. Synthesis 2010; 407

      See, for example:
    • 6a Sarkisyan ZM, Sadikov KD, Smirnov AS, Kuzhaeva AA, Makarenko SV, Anisimova NA, Deiko LI, Berestovitskaya VM, Russian VM. J. Org. Chem. 2004; 40: 908
    • 6b Tuan DT, Tung DT, Langer P. Synlett 2006; 2812
    • 6c Ganesh M, Namboothiri IN. N. Tetrahedron 2007; 63: 11973
  • 7 Shen Y, Yang B. Synth. Commun. 1993; 23: 1
    • 8a Ballini R, Castagnani R, Petrini M. J. Org. Chem. 1992; 57: 2160
    • 8b Ballini R, Bosica G, Forconi P. Tetrahedron 1996; 52: 1677
    • 8c Ballini R, Bosica G. J. Org. Chem. 1997; 62: 425
    • 8d Ballini R, Bosica G, Parrini M. Chem. Lett. 1999; 1105
    • 8e Ballini R, Bigi F, Giorgi E, Maggi R, Sartori G. J. Catal. 2000; 191: 348
    • 8f Ballini R, Bosica G, Livi D, Palmieri A, Maggi R, Sartori G. Tetrahedron Lett. 2003; 44: 2271
    • 8g Ballini R, Fiorini D, Gil MV, Palmieri A. Tetrahedron 2004; 60: 2799
    • 8h Ballini R, Barboni L, Palmieri A. Synlett 2007; 3019
    • 8i Ballini R, Bosica G, Palmieri A, Pizzo F, Vaccaro L. Green Chem. 2008; 10: 541
    • 8j Ballini R, Noé M, Perosa A, Selva M. J. Org. Chem. 2008; 73: 8520
  • 9 Usually, the dehydration of bromonitroalkanols is performed under basic conditions, see ref. 6.
  • 10 Typical Procedure for the Synthesis of Compounds 5 The catalyst (0.56 g, 0.3 mmol) was slowly added at r.t. to a mechanically stirred mixture of the bromonitromethane (6, 1 mmol, 0.155 g, pure 90%) and the requisite aldehyde 1 (1 mmol), and the reaction was stirred for the appropriate time (see Table). The mixture was then treated with EtOAc (5 mL), and the catalyst was filtered off and washed with additional EtOAc (10 mL). The solution was concentrated under reduced pressure to a volume of 3 mL and then treated with Ac2O (306 mg, 3 mmol) and Amberlyst 15 (0.5 g) and stirred, at r.t., for an additional 1.5 h. Finally, the Amberlyst 15 was removed by filtration, washing with EtOAc (7 mL), and the solution was concentrated under vacuum giving the crude product 5 which was purified by flash chromatography (hexane–EtOAc = 9:1). (Z)-1-Bromo-1-nitrohept-1-ene (5a) Light yellow oil. IR (neat): ν = 3045, 1551, 1325, 1261, 942, 722 cm–1. 1H NMR (400 MHz, CDCl3): δ = 0.91 (t, 3 H, J = 6.8 Hz), 1.30–1.40 (m, 4 H), 1.51–1.61 (m, 2 H), 2.37 (q, 2 H, J = 7.3 Hz), 7.67 (t, 1 H, J = 7.3 Hz). 13C NMR (100MHz, CDCl3): δ = 14.1, 22.5, 27.3, 31.3, 31.6, 131.2, 141.6. MS (EI, 70 eV): m/z (%) = 165, 142, 119, 95, 69, 55, 41 (100), 39, 30. Anal. Calcd for C7H12BrNO2 (222.08): C, 37.86; H, 5.45; N, 6.31. Found: C, 37.91; H, 5.49; N, 6.28. (Z)-1-Bromo-1-nitronon-1-ene (5b) Light yellow oil. IR (neat): ν = 3040, 1542, 1321, 1254, 960, 768 cm–1. 1H NMR (400 MHz, CDCl3): δ = 0.89 (t, 3 H, J = 6.8 Hz), 1.23–1.41 (m, 8 H), 1.50–1.61 (m, 2 H), 2.37 (q, 2 H, J = 7.3 Hz), 7.66 (t, 1 H, J = 7.3 Hz). 13C NMR (100 MHz, CDCl3): δ = 14.3, 22.8, 27.6, 29.1, 29.4, 31.3, 31.9, 131.2, 141.6. MS (EI, 70 eV): m/z (%) = 234, 121, 93, 81, 67, 55, 43 (100), 41, 39, 29. Anal. Calcd for C9H16BrNO2 (250.13): C, 43.22; H, 6.45; N, 5.60. Found: C, 43.27; H, 6.49; N, 5.58. (Z)-(2-Bromo-2-nitrovinyl)cyclohexane (5c) Light yellow oil. IR (neat): ν = 3030, 1539, 1320, 971, 960, 761 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.18–1.44 (m, 6 H), 1.65–1.84 (m, 4 H), 2.39–2.53 (m, 1 H), 7.48 (d, 1 H, J = 9.8 Hz). 13C NMR (100 MHz, CDCl3): δ = 25.3, 25.7, 30.8, 40.8, 129.7, 145.3. MS (EI, 70 eV): m/z (%) = 218, 216, 137, 119, 97, 91, 81, 79, 71, 69, 55 (100), 41, 39. Anal. Calcd for C8H12BrNO2 (234.09): C, 41.05; H, 5.17; N, 5.98. Found: C, 41.09; H, 5.21; N, 5.96. (Z)-(4-Bromo-4-nitrobut-3-enyl)benzene (5d) Light yellow oil. IR (neat): ν = 3035, 1618, 1525, 1331, 937, 750, 724, 698 cm–1. 1H NMR (400 MHz, CDCl3): δ = 2.71 (q, 2 H, J = 7.7 Hz), 2.88 (t, 2 H, J = 7.7 Hz), 7.17–7.36 (m, 5 H), 7.67 (t, 1 H, J = 7.7 Hz). 13C NMR (100 MHz, CDCl3): δ = 33.0, 33.6, 127.0, 128.5, 129.0, 131.8, 139.7, 140.2. MS (EI, 70 eV): m/z (%) = 240, 238, 129, 91 (100), 65. Anal. Calcd for C10H10BrNO2 (256.10): C, 46.90; H, 3.94; N, 5.47. Found: C, 46.88; H, 3.97; N, 5.44. (Z)-Ethyl 3-Bromo-3-nitroacrylate (5e) Light yellow oil. IR (neat): ν = 1733, 1622, 1552, 1323 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.35 (t, 3 H, J = 7.3 Hz), 4.34 (q, 2 H, J = 7.3 Hz), 7.74 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 14.2, 62.8, 125.8, 139.3, 162.2. MS (EI, 70 eV): m/z (%) = 180, 178, 166, 164, 151, 149, 133, 131, 106, 104, 69, 53, 29 (100). Anal. Calcd for C5H6BrNO4 (224.01): C, 26.81; H, 2.70; N, 6.25. Found: C, 26.86; H, 2.72; N, 6.22. (Z)-1-(2-Bromo-2-nitrovinyl)-4-tert-butylbenzene (5f) Yellow solid, mp 50–52 °C. IR (neat): ν = 3030, 1599, 1530, 1325, 953, 834, 762 cm–1. 1H NMR (400 MHz, CDCl3): δ = 1.35 (s, 9 H), 7.51 (d, 2 H, J = 8.5 Hz), 7.86 (d, 2 H, J = 8.5 Hz), 8.64 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 31.3, 35.4, 126.3, 127.3, 127.5, 131.3, 136.7, 156.3. MS (EI, 70 eV): m/z (%) = 285, 283, 270, 268, 222, 220, 143 (100), 128, 115, 57. Anal. Calcd for C12H14BrNO2 (284.15): C, 50.72; H, 4.97; N, 4.93. Found: C, 50.76; H, 5.00; N, 4.90. (Z)-1-(2-Bromo-2-nitrovinyl)-3-methoxybenzene (5g) Yellow solid, mp 68–70 °C. IR (neat): ν = 3070, 3029, 1607, 1553, 1331, 1176, 897, 743 cm–1. 1H NMR (400 MHz, CDCl3): δ = 3.86 (s, 3 H), 7.07 (d, 1 H, J = 7.7 Hz), 7.38–7.46 (m, 3 H), 8.61 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 55.6, 115.8, 118.0, 124.0, 128.5, 130.2, 131.5, 136.6, 159.9. MS (EI, 70 eV): m/z (%) = 259, 257, 212, 210, 150, 148, 132 (100), 102, 89, 77, 63. Anal. Calcd for C9H8BrNO3 (258.07): C, 41.89; H, 3.12; N, 5.43. Found: C, 41.93; H, 3.10; N, 5.40. (Z)-1-(2-Bromo-2-nitrovinyl)-4-methoxybenzene (5h) Yellow solid, mp 59–61 °C. IR (neat): ν = 3041, 1520, 1310, 1261, 1181, 957, 825 cm–1. 1H NMR (400 MHz, CDCl3): δ = 3.88 (s, 3 H), 7.00 (d, 2 H, J = 8.5 Hz), 7.92 (d, 2 H, J = 8.5 Hz), 8.63 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 55.8, 114.8, 122.6, 125.6, 133.7, 136.6, 163.0. MS (EI, 70 eV): m/z (%) = 259, 257, 212, 210, 132 (100), 117, 89, 63. Anal. Calcd for C9H8BrNO3 (258.07): C, 41.89; H, 3.12; N, 5.43. Found: C, 41.93; H, 3.09; N, 5.45. (Z)-1-Bromo-2-(2-bromo-2-nitrovinyl)benzene (5i) Yellow waxy solid. IR (neat): ν = 3078, 3035, 1606, 1582, 1532, 1300, 898, 764, 733, 703 cm–1. 1H NMR (400 MHz, CDCl3): δ = 7.35 (t, 1 H, J = 7.7 Hz), 7.44 (t, 1 H, J = 7.7 Hz), 7.69 (d, 1 H, J = 7.7 Hz), 7.86 (d, 1 H, J = 7.7 Hz), 8.77 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 125.7, 127.7, 130.6, 131.3, 131.6, 132.5, 133.5, 136.2. MS (EI, 70 eV): m/z (%) = 309, 307, 305, 262, 260, 258, 228, 226, 198, 196, 182, 180 (100), 147, 101, 75, 50. Anal. Calcd for C8H5Br2NO2 (306.94): C, 31.30; H, 1.64; N, 4.56. Found: C, 31.33; H, 1.65; N, 4.54. (Z)-5-(2-Bromo-2-nitrovinyl)-1,2,3-trimethoxybenzene (5j) Orange solid, mp 113–115 °C. IR (neat): ν = 3075, 3035, 1603, 1577, 1522, 1333, 1246, 1125, 824, 618 cm–1. 1H NMR (400 MHz, CDCl3): δ = 3.91 (s, 6 H), 3.93 (s, 3 H), 7.19 (s, 2 H), 8.59 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 56.4, 56.5, 61.3, 105.9, 108.9, 125.2, 127.1, 131.9, 136.7, 141.8, 153.4. MS (EI, 70 eV): m/z (%) = 319, 317, 272, 270, 257, 255, 192, 177 (100), 149, 134, 119, 63. Anal. Calcd for C11H12BrNO5 (318.12): C, 41.53; H, 3.80; N, 4.40. Found: C, 41.57; H, 3.82; N, 4.38. (Z)-2-Bromo-5-(2-bromo-2-nitrovinyl)furan (5k) Yellow solid, mp 87–89 °C. IR (neat): ν = 3134, 3036, 1618, 1537, 1505, 1348, 1292, 1025, 948, 818, 786, 645 cm–1. 1H NMR (400 MHz, CDCl3): δ = 6.61 (d, 1 H, J = 3.4 Hz), 7.37 (d, 1 H, J = 3.4 Hz), 8.50 (s, 1 H). 13C NMR (100 MHz, CDCl3): δ = 115.8, 122.3, 124.0, 125.1, 129.6, 148.6. MS (EI, 70 eV): m/z (%) = 299, 297, 295, 225, 223, 221, 135, 133, 79, 63 (100). Anal. Calcd for C6H3Br2NO3 (296.90): C, 24.27; H, 1.02; N, 4.72. Found: C, 24.30; H, 1.03; N, 4.69.

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Scheme 1
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Scheme 2 Reagents and conditions: a) SolFC, carbonate on silica, r.t., 4.5 h; b) Amberlyst 15, EtOAc, r.t., 1.5 h.