Small Organophosphorus-Selenium
Heterocycles from the Selenation of Conjugated Ketones
and Enals

Guoxiong Hua; Alexandra M. Z. Slawin; J. Derek Woollins

doi:10.1055/s-0031-1290349

LETTER

Small Organophosphorus-Selenium Heterocycles from the Selenation of Conjugated Ketones and Enals

Guoxiong Hua, Alexandra M. Z. Slawin, J. Derek Woollins*
EastChem School of Chemistry, University of St Andrews, Fife, KY16 9ST, UK
Fax: +44(1334)463384; e-Mail: jdw3@st-and.ac.uk;

Abstract

All articles of this category

Abstract

Reaction of 2,4-bis(phenyl)-1,3-diselenadiphosphetane-2,4-diselenide [Woollins’ reagent, WR] with equimolar amount of α,β-unsaturated ketones [R^¹C(O)C=CR^² (R^¹ = aryl or alkyl; R^² = aryl)] leads to a series of novel five-membered C₃P(Se)Se heterocycles 1-8 in 48-95% isolated yields. Furthermore, WR reacts with one equivalent of aromatic conjugated enals [RC=CC=O, R = Ph and 2-MeOC₆H₄] to give five-membered C₃P(Se)Se heterocycles 9 and 10 via the cleavage/cyclic extension of WR molecular ring. All new compounds have been characterised spectroscopically (^³¹P NMR, ⁷⁷Se NMR, ^¹H NMR, ^¹³C NMR, IR and mass spectroscopy) and one representative X-ray structure is reported.

Key words

selenium - phosphorus - heterocycles - Woollins’ reagent - X-Ray structure

Full Text

References

References and Notes

<A NAME="RB72411TX-1">1</A> Wirth T. Organoselenium Chemistry: Modern Development in Organic Synthesis Springer; Berlin: 2000.

<A NAME="RB72411TX-2A">2a</A> Srivastava PC. Robin RK. J. Med. Chem. 1983, 26: 445

<A NAME="RB72411TX-2B">2b</A> Kumar Y. Green R. Borysko KZ. Wise DS. Wotring L. Townsend LB. J. Med. Chem. 1993, 36: 3843

<A NAME="RB72411TX-2C">2c</A> Koketsu M. Hishihara H. Wu W. Murakami K. Saiki I. Eur. J. Pharm. Sci. 1999, 9: 156

<A NAME="RB72411TX-2D">2d</A> Wu W. Murakami K. Koketsu M. Yamada Y. Saiki I. Anticancer Res. 1999, 19: 5375

<A NAME="RB72411TX-3A">3a</A> Garin J. Adv. Heterocycl. Chem. 1995, 62: 249

<A NAME="RB72411TX-3B">3b</A> Uemoto T. Adv. Heterocycl. Chem. 1995, 64: 323

<A NAME="RB72411TX-4A">4a</A> Back TG. Organoselenium Chemistry, A Practical Approach Oxford University Press; Oxford: 1999.

<A NAME="RB72411TX-4B">4b</A> Mlochowski J. Phosphorus, Sulfur Silicon 1998, 191: 136

<A NAME="RB72411TX-4C">4c</A> Tiecco M. Top. Curr. Chem. 2000, 208: 7

<A NAME="RB72411TX-4D">4d</A> Wirth T. Angew. Chem. Int. Ed. 2000, 208: 3742

<A NAME="RB72411TX-4E">4e</A> Mlochowski J. Brzaszcz M. Giurg M. Palus J. Wojtowicz H. Eur. J. Org. Chem. 2003, 4329:

<A NAME="RB72411TX-5">5</A> Hua G. Woollins JD. Angew. Chem. Int. Ed. 2009, 48: 1368

<A NAME="RB72411TX-6">6</A> Gray IP. Bhattacharyya P. Slawin AMZ. Woollins JD. Chem. Eur. J. 2005, 11: 6221

<A NAME="RB72411TX-7">7</A> Hua G. Henry JB. Li Y. Mount AR. Slawin AMZ. Woollins JD. Org. Biomol. Chem. 2010, 8: 1655

<A NAME="RB72411TX-8">8</A> Hua G. Li Y. Fuller AL. Slawin AMZ. Woollins JD. Eur. J. Org. Chem. 2009, 1612:

<A NAME="RB72411TX-9">9</A> Hua G. Fuller AL. Li Y. Slawin AMZ. Woollins JD. New J. Chem. 2010, 34: 1565

<A NAME="RB72411TX-10">10</A> Hua G. Fuller AL. Slawin AMZ. Woollins JD. Eur. J. Org. Chem. 2010, 2707:

<A NAME="RB72411TX-11">11</A> Hua G. Fuller AL. Slawin AMZ. Woollins JD. Polyhedron 2011, 30: 805

<A NAME="RB72411TX-12">12</A> Hua G. Fuller AL. Slawin AMZ. Woollins JD. Eur. J. Org. Chem. 2011, 3067:

<A NAME="RB72411TX-13">13</A> Hua G. Griffin JM. Ashbrook SE. Slawin AMZ. Woollins JD. Angew. Chem. Int. Ed. 2011, 50: 4123

<A NAME="RB72411TX-14">14</A> Hua G. Cordes DB. Li Y. Slawin AMZ. Woollins JD. Tetrahedron Lett. 2011, 52: 3311

<A NAME="RB72411TX-15">15</A> Hua G. Woollins JD. Tetrahedron Lett. 2007, 48: 3677

<A NAME="RB72411TX-16">16</A> Hua G. Li Y. Slawin AMZ. Woollins JD. Dalton Trans. 2007, 1477:

<A NAME="RB72411TX-17">17</A> Hua G. Li Y. Slawin AMZ. Woollins JD. Acta Crystallogr., Sect. E 2008, E64: o184

Crystallographic Data for Compound 1a: C₂₁H₁₇PSe₂, M = 458.24, monoclinic, space group P2_1/n, a = 9.948 (3), b = 16.347 (7), c = 11.640 (4) Å, β = 102.399 (8)˚, U = 1848.7 (11) Å^³, Z = 4, µ = 1.646 mm^-¹, 12616 reflections, 3627 unique (R _int = 0.038); R ₁ = 0.044, wR ₂ = 0.106.

<A NAME="RB72411TX-19">19</A> Bhattacharyya P. Slawin AMZ. Woollins JD. J. Organomet. Chem. 2001, 623: 116

<A NAME="RB72411TX-20A">20a</A> Bhattacharyya P. Slawin AMZ. Woollins JD. Chem. Eur. J. 2002, 8: 2705

<A NAME="RB72411TX-20B">20b</A> Bhattacharyya P. Slawin AMZ. Woollins JD. Dalton Trans. 2001, 300:

<A NAME="RB72411TX-20C">20c</A> Bhattacharyya P. Novosad J. Phillips JR. Slawin AMZ. Williams DJ. Woollins DJ. Dalton Trans. 1995, 1607:

<A NAME="RB72411TX-21">21</A> Shore JT. Pennington WT. Noble MC. Cordes AW. Phosphorus, Sulfur Silicon Relat. Elem. 1988, 39: 153

<A NAME="RB72411TX-22">22</A> Weng Z. Leong WK. Vittal JJ. Goh LY. Organometallics 2003, 22: 1465

<A NAME="RB72411TX-23">23</A> Pilkington MJ. Slawin AMZ. Williams DJ. Wood PT. Woollins JD. Heteroatom. Chem. 1990, 1: 351

Experimental Section: Unless otherwise stated, all reactions were carried out under an oxygen-free nitrogen atmosphere using pre-dried solvents and standard Schlenk techniques, subsequent chromatographic and workup procedures were performed in air. ^¹H NMR (270 MHz), ^¹³C NMR (67.9 MHz), ^³¹P-{^¹H} NMR (109 MHz) and ⁷⁷Se-{^¹H} (51.4 MHz referenced to external Me₂Se) NMR spectra were recorded at 25 ˚C (unless stated otherwise) on a JEOL GSX 270 spectrometer. IR spectra were recorded as KBr pellets in the range of 4000-250 cm^-¹ on a Perkin-Elmer 2000 FTIR/Raman spectrometer. Microanalysis was performed by the University of St-Andrews microanalysis service. Mass spectrometry was performed by the EPSRC National Mass Spectrometry Service Centre, Swansea and the University of St Andrews Mass Spectrometry Service. X-ray crystal data for 1, were collected using a Rigaku SCXMIni Mercury CCD system. Intensity data were collected using ω steps accumulating area detector images spanning at least a hemisphere of reciprocal space. The data were corrected
for Lorentz polarisation effects. Absorption effects were corrected on the basis of multiple equivalent reflections or by semi-empirical methods. Structures were solved by direct methods and refined by full-matrix least-squares against F^² by using the program SHELXTL.^²5 Hydrogen atoms were assigned riding isotropic displacement parameters and constrained to idealised geometries. The data (CCDC 855701) can be obtained free of charge via www.ccdc.cam.ac.uk/conts/retrieving.html or from the Cambridge Crystallographic Data centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax +44(1223)336033; e-mail: deposit@ccdc.cam.ac.uk.
General Procedure for Synthesis of Compounds 1-8 from the Selenation of α , β-Unsaturated Ketones: A mixture of α,β-unsaturated ketone (1.0 mmol) and WR (0.54 g, 1.0 mmol) in anhyd toluene (20 mL) was refluxed for 7 h. Red suspension disappeared and a pale brown solution was formed along with small amount of grey elemental selenium precipitate. Upon cooling to r.t. and removing the unreacted solid by filtration the filtrate was dried in evaporator and purified by silica gel column (eluent: EtOAc-CH₂Cl₂, 1:1) to give compounds 1-8.
Compound 1: yellow paste (425 mg) in 92% isolated yield. IR (KBr): 1599 (m, C=C), 1490 (m), 1434 (m), 1088 (m), 749 (s), 690 (s), 595 (m), 513 (m) cm^-¹. A pair of stereoisomers was found in ca. 4:6 intensity ratio. ^¹H NMR (CD₂Cl₂): δ = 8.21 (dd, 2 × 4 H, ArH), 7.01-7.59 (m, 2 × 10 H, ArH), 6.65 (dd, J _H,H = 3.6 Hz, J _P,H = 32.2 Hz, 1 H, HC=C), 6.57 (dd, J _H,H = 3.6 Hz, J _P,H = 32.2 Hz, 1 H, HC=C), 5.52 (dd, J _H,H = 3.6 Hz, J _P,H = 18.2 Hz, 1 H, HC), 5.09 (dd, J _H,H = 3.6 Hz, J _P,H = 18.2 Hz, 1 H, HC). ^¹³C NMR (CD₂Cl₂): δ = 142.3, 142.0, 141.8, 141.7, 136.1, 134.6, 134.1, 134.0, 133.1, 132.9, 132.8, 132.4, 132.1, 131.8, 131.7, 129.4, 129.0, 129.0, 128.8, 128.6, 128.5, 128.3, 128.2, 128.0, 127.9, 127.8, 127.3, 127.2, 125.4, 124.9, 71.6 (d, J _P,C = 30.1 Hz), 65.8 (d, J _P,C = 29.1 Hz). ^³¹P NMR (CD₂Cl₂): δ = 72.4 (s, J _P-Se = 346 Hz, J _P=Se = 806 Hz), 71.4 (s, J _P-Se = 346 Hz, J _P=Se = 786 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 408.9 (d, J _P-Se = 346 Hz), 391.5 (d, J _P-Se = 346 Hz), -170.8 (d, J _P=Se = 786 Hz), -187.5 (d, J _P=Se = 806 Hz). MS (ESI⁺): m/z = 483 [M + Na]⁺. MS (CI⁺): m/z = 461 [M + H]⁺. HRMS (CI⁺): m/z [M + H]⁺ calcd for C₂₁H₁₈PSe₂: 460.9471; found: 460.9473.
Compound 2: yellowish milky solid (466 mg) in 95% isolated yield. IR (KBr): 1607 (m, C=C), 1510 (s, C=C), 1435 (m), 1303 (m), 1251 (s), 1177 (m), 1090 (m), 1030 (m), 831 (m), 746 (m), 688 (m), 596 (m), 521 (m) cm^-¹. A pair of stereoisomers was found in ca. 4:6 intensity ratio. ^¹H NMR (CD₂Cl₂): δ = 8.22 (dd, J _H,H = 6.9 Hz, 2 × 4 H, ArH), 6.92-7.75 (m, 2 × 10 H, ArH), 6.65 (dd, 2 × 1 H, HC=C), 5.45 (dd, J _P,H = 17.6 Hz, 2 × 1H, HC), 3.80 (s, 3 H, OMe), 3.69 (s, 3 H, OMe). ^¹³C NMR (CD₂Cl₂): δ = 141.8, 141.7, 141.4, 141.3, 136.2, 133.2, 133.0, 132.4 (d, J _P,C = 3.1 Hz), 132.2 (d, J _P,C = 3.1 Hz), 131.9, 131.7, 130.6, 130.5, 129.5, 129.4, 129.1, 129.0, 128.9, 128.7, 128.1, 127.9, 127.4, 127.3, 125.8, 125.3, 71.0 (d, J _P,C = 31.1 Hz), 65.2 (d, J _P,C = 29.1 Hz), 55.3. ^³¹P NMR (CD₂Cl₂): δ = 73.0 (s, J _P-Se = 336 Hz, J _P=Se = 801 Hz), 71.6 (s, J _P-Se = 345 Hz, J _P=Se = 784 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 406.7 (d, J _P-Se = 336 Hz), 390.0 (d, J _P-Se = 345 Hz), -174.1 (d, J _P=Se = 784 Hz), -188.2 (d, J _P=Se = 801 Hz). MS (CI⁺): m/z = 491 [M + H]⁺. HRMS (CI⁺): m/z [M + H]⁺ calcd for C₂₂H₂₀OPSe₂: 490.9577; found: 490.9582.
Compound 3: pale yellow paste (320 mg) in 81% isolated yield. IR (KBr): 1555 (w, C=C), 1489 (m), 1433 (m), 1090 (m), 764 (m), 745 (m), 689 (s), 558 (m), 526 (m), 505 (m) cm^-¹. Four stereoisomers were found in ca. 4:4:2:2 intensity ratio. ^¹H NMR (CD₂Cl₂): δ = 7.98-8.19 (m, 4 × 2 H, ArH), 6.91-7.64 (m, 4 × 8 H, ArH), 6.38-6.63 (m, 4 × 1 H, CH), 5.92-6.19 (m, 4 × 1 H, CH), 2.32-2.34 (s, 4 × 3 H, Me). ^¹³C NMR (CD₂Cl₂): δ = 141.3, 141.1, 140.0, 139.9, 138.3, 138.2, 134.5, 134.4, 133.1, 132.9, 132.4, 132.3, 132.0, 131.7, 131.5, 129.4, 129.3, 129.1, 128.8, 128.7, 128.6, 128.4, 128.2, 128.1, 128.0, 127.9, 127.7, 125.3, 71.2, 70.8, 65.3, 64.9, 21.9, 21.2. ^³¹P NMR (CD₂Cl₂): δ = 75.6 (s,
J _P-Se = 390 Hz, J _P=Se = 765 Hz), 75.3 (s, J _P-Se = 336 Hz, J _P=Se = 801 Hz), 74.7 (s, J _P-Se = 346 Hz, J _P=Se = 782 Hz), 61.7 (s,
J _P-Se = 390 Hz, J _P=Se = 770 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 449.7 (d, J _P-Se = 390 Hz), 443.9 (d, J _P-Se = 390 Hz), 421.4 (d, J _P-Se = 336 Hz), 405.5 (d, J _P-Se = 346 Hz), -111.7 (d, J _P=Se = 770 Hz), -125.9 (d, J _P=Se = 765 Hz), -156.7 (d, J _P=Se = 782 Hz), -182.8 (d, J _P=Se = 801 Hz). MS (EI⁺): m/z = 398 [M]⁺. HRMS (EI⁺): m/z [M]⁺ calcd for C₁₆H₁₅P⁷⁶Se₂: 389.9290; found: 389.99293.
Compound 4: orange solid (414 mg) in 84% isolated yield. IR (KBr): 1601 (m, C=C), 1505 (vs, C=C), 1434 (s), 1224 (s), 1158 (m), 1090 (m), 834 (s), 745 (s), 687 (m), 526 (m), 508 (s) cm^-¹. A pair of stereoisomers was found in ca. 1:2 intensity ratio. ^¹H NMR (CD₂Cl₂): δ = 8.14-8. 22 (d, J _H,H = 7.2 Hz, 2 × 2 H, ArH), 6.74-7.69 (m, 2 × 11 H, ArH), 6.40-6.52 (d, 2 × 1 H, CH), 5.44-5.50 (d, 2 × 1 H, CH), 2.38 (s, 3 H, Me), 2.37 (s, 3 H, Me). ^¹³C NMR (CD₂Cl₂): δ = 164.6, 164.3, 161.0, 160.8, 140.0, 133.1, 132.9, 132.5, 132.3, 131.8, 131.6, 131.0, 130.3, 129.9, 129.7, 129.1, 128.8, 128.6, 128.5, 128.1, 127.9, 127.6, 127.2, 127.1, 124.1, 123.8, 70.9, 70.5, 65.1, 64.6, 21.1, 21.0. ^³¹P NMR (CD₂Cl₂): δ = 72.0 (s, J _P-Se = 340 Hz, J _P=Se = 803 Hz), 70.7 (s, J _P-Se = 357 Hz, J _P=Se = 789 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 400.7 (d, J _P-Se = 340 Hz), 386.5 (d, J _P-Se = 357 Hz), -177.8 (d, J _P=Se = 789 Hz), -191.1 (d, J _P=Se = 803 Hz). MS (CI⁺): m/z = 493
[M + H]⁺. MS (EI⁺) m/z = 492 [M]⁺. HRMS (EI⁺): m/z [M]⁺ calcd for C₂₂H₁₈FP⁷⁶Se₂: 483.9509; found: 483.9504.
Compound 5: yellow solid (403 mg) in 83% isolated yield. Two stereoisomers were found in ca. 1:2 intensity ratio. IR (KBr): 1598 (w, C=C), 1491 (m, C=C), 1434 (m, C=C), 1185 (w), 1165 (w), 1128 (w), 1088 (s), 939 (s), 764 (s), 745 (s), 688(vs), 630 (m), 595 (s), 506 (s, P=Se) cm^-¹. ^¹H NMR (CDCl₃): δ = 7.47-7.63 (m, 2 × 2 H, ArH), 7.30-7.37 (m, 2 × 5 H, ArH), 7.12-7.21 (m, 2 × 4 H, ArH), 7.04-7.11 (m, 2 × 4 H, ArH), 6.93-6.96 (m, 2 × 2 H, ArH), 7.05 (d, J = 3.0 Hz, 1 H, CH), 6.95 (d, J = 3.0 Hz, 1 H, CH), 6.66 (dd, ^³ J _H,H = 3.0 Hz, ^³ J _P,H = 15.0 Hz, 1 H, CH), 6.36 (dd, ^³ J _H,H = 3.0 Hz, ^² J _P,H = 32.0 Hz, 1 H, CH). ^¹³C NMR (CDCl₃): δ = 141.0, 136.0, 135.8, 133.1, 133.0, 132.6, 132.4, 132.0, 129.0, 128.8, 128.3, 128.2, 127.9, 127.8, 127.0, 125.2, 70.3 (d, ^¹ J _P,C = 29 Hz). ^³¹P NMR (CDCl₃): δ = 70.3 (s, J _P-Se = 338 Hz, J _P=Se = 803 Hz), 69.9 (s, J _P-Se = 350 Hz, J _P=Se = 782 Hz). ⁷⁷Se NMR (CDCl₃): δ = 374.0 (d, J _P-Se = 338 Hz), 354.9 (d, J _P-Se = 350 Hz), -170.7 (d, J _P=Se = 782 Hz), -188.0 (d,
J _P=Se = 803 Hz). MS (ES⁺): m/z = 507 [M + Na]⁺. Anal. Calcd for C₂₃H₁₉PSe₂ (484.29): C, 57.04; H, 3.95. Found: C, 57.01; H, 3.99.
Compound 6: brown solid (340 mg) in 67% yield. ^³¹P NMR spectrum revealed four stereoisomers in ca. 4:2:1:2 intensity ratio. IR (KBr): 1691 (m, C=C), 1594 (m, C=C), 1518 (s, C=C), 1434 (m), 1343 (s), 1089 (m), 851 (s), 689 (s), 596 (m), 508 cm^-¹. ^¹H NMR (CD₂Cl₂): δ = 7.54-8.30 (m, 4 × 10 H, thienyl-H, ArH), 7.00-7.32 (m, 2 H, thienyl-H), 6.75-6.93 (m, 4 × 1 H, =CH), 3.26-3.44 (m, 4 × 1 H, SeCH). ^¹³C NMR (CD₂Cl₂): δ = 150.4, 148.0, 147.7, 147.3, 143.5,142.1, 141.2, 139.2, 133.1, 133.0, 132.9, 132.7, 132.5, 132.0, 131.8, 129.1, 128.9, 128.8, 128.7, 128.6, 128.3, 128.1, 127.9, 127.8, 127.4, 127.1, 125.0, 124.6, 124.2, 123.9, 123.6, 67.6, 67.1, 61.8, 61.4, 41.1, 23.9. ^³¹P NMR (CD₂Cl₂): δ = 73.7 (s, J _P-Se = 331 Hz, J _P=Se = 832 Hz), 71.8 (s, J _P-Se = 340 Hz, J _P=Se = 796 Hz), 61.0 (s, J _P-Se = 366 Hz, J _P=Se = 793 Hz), 54.1 (s, J _P-Se = 380 Hz, J _P=Se = 782 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 487.1 (d, J _P-Se = 381 Hz), 473.1 (d, J _P-Se = 365 Hz), 414.8 (d, J _P-Se = 329 Hz), 405.6 (d, J _P-Se = 341 Hz), -83.2 (d, J _P=Se = 782 Hz), -161.5 (d, J _P=Se = 793 Hz),
-166.7 (d, J _P=Se = 796 Hz), -190.8 (d, J _P=Se = 832 Hz). MS (EI⁺): m/z = 511 [M]⁺. HRMS (EI⁺): m/z [M]⁺ calcd for C₁₉H₁₄O₂NPS⁷⁴Se₂: 498.8927; found: 498.8933.
Compound 7: dark red solid (250 mg)in 50% yield. ^³¹P NMR spectrum revealed two stereoisomers in ca. 3:1 intensity ratio. IR (KBr): 1634 (s, C=C), 1557 (m, C=C), 1539 (m, C=C), 1470 (s), 1435 (m), 1408 (m), 1220 (m), 1071 (m), 781 (m), 748 (m), 686 (s)cm^-¹. ^¹H NMR (CD₂Cl₂): δ = 6.96-8.15 (m, 2 × 9 H, ArH), 6.41 (d, J _P,H = 16.5 Hz, 1 H, CH), 6.40 (d, J _P,H =16.5 Hz, 1 H, CH), 3.77-4.04 (m, 2 × 1 H, CH), 3.37 (s, 6 H, Me), 2.94 (s, 6 H, Me). ^¹³C NMR (CD₂Cl₂): δ = 142.6, 140.5, 138.2, 134.8, 132.7, 132.5, 132.3, 132.0, 131.4, 131.2, 130.2, 130.0, 128.8, 128.6, 127.2, 126.1, 61.1, 56.6, 37.1, 34.1. ^³¹P NMR (CD₂Cl₂): δ = 57.0 (s, J _P-Se = 333 Hz, J _P=Se = 787 Hz), 56.1 (s, J _P-Se = 369 Hz, J _P=Se = 785 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 455.2 (d, J _P-Se = 369 Hz), 450.0 (d, J _P-Se = 333 Hz), -131.2 (d, J _P=Se = 785 Hz), -131.6 (d, J _P=Se = 787 Hz). MS (EI⁺): m/z = 505 [M]⁺. HRMS (EI⁺): m/z [M]⁺ calcd for C₁₇H₁₇BrPSe₂: 504.8612; found: 504.8615.
Compound 8: pale yellow solid (224 mg) in 48% yield. Multi-NMR spectrum revealed four stereoisomers in ca. 3:4:2:2 extensity ratio. IR (KBr): 1657 (s, C=C), 1432 (s), 1226 (m), 1089 (s), 819 (m), 699(vs), 595 (m), 507 (s) cm^-¹. ^¹H NMR (CD₂Cl₂): δ = 8.22-7.01 (m, 4 × 9 H, thienyl-H + ArH), 6.65-6.94 (m, 4 × 2 H, thienyl-H), 5.65-5.75 (m, 4 × 1 H, =CH), 3.29-3.29 (m, 4 × 1 H, SeCH). ^¹³C NMR (CD₂Cl₂): δ = 144.2, 143.8, 143.6, 143.2, 138.9, 136.1, 135.2, 134.6, 133.7, 133.6, 133.0, 132.9, 132.7, 132.5, 132.4, 132.1, 131.7, 128.8, 128.3, 128.2, 128.0, 127.9, 127.3, 126.9, 125.2, 125.1, 123.7, 123.5, 44.5, 43.8, 43.3, 41.0. ^³¹P NMR (CD₂Cl₂): δ = 71.1 (s, J _P-Se = 336 Hz, J _P=Se = 810 Hz), 69.1 (s, J _P-Se = 341 Hz, J _P=Se = 792 Hz), 61.0 (s, J _P-Se = 377 Hz, J _P=Se = 789 Hz), 60.5 (s, J _P-Se = 393 Hz, J _P=Se = 777 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 477.2 (d, J _P-Se = 377 Hz), 412.7 (d, J _P-Se = 341 Hz), 407.3 (d, J _P-Se = 336 Hz), 398.5 (d, J _P-Se = 393 Hz), -142.5 (d, J _P=Se = 777 Hz), -166.4 (d, J _P=Se = 789 Hz), -176.7 (d, J _P=Se = 792 Hz), -203.3 (d, J _P=Se = 810 Hz). MS (EI⁺): m/z = 472 [M]⁺. HRMS (EI⁺): m/z [M]⁺ calcd for C₁₇H₁₃PS₂ ⁷⁴Se₂: 459.8640; found: 459.8635.
General Procedure for Synthesis of Compounds 9 and 10 from the Selenation of Aromatic α,β-Unsaturated Enals: A red solution of aromatic enal (1.0 mmol) and WR (0.54 g, 1.0 mmol) in anhyd toluene (20 mL) was refluxed for 7 h. Red suspension disappeared and a pale brown solution along with small amount of grey elemental selenium precipitate was formed. Upon cooling to r.t. the mixture was dried in evaporator and the residue was purified by silica gel column (eluent: EtOAc-CH₂Cl₂, 1:5) to give compounds 9 and 10.
Compound 9: reddish yellow paste (600 mg) in 79% isolated yield. ^³¹P NMR spectrum revealed a mixture of four stereoisomers in ca. 5:7:5:3 intensity ratio. IR (KBr): 1673 (s, C=C), 1491 (m), 1450 (m), 1434 (m), 1121 (m), 1088 (m), 961 (m), 764(vs), 693(vs), 591 (m), 511 (m)cm^-¹. ^¹H NMR (CD₂Cl₂): δ = 7.92-8.11 (m, 2 H, ArH), 7.07-7.58 (m, 8 H, ArH), 6.84-6.96 (m, 1 H, CH), 6.58-6.66 (m, 1 H, CH), 6.11-6.16 (m, 1 H, CH). ^¹³C NMR (CD₂Cl₂): δ = 137.0, 136.7, 134.0, 133.5, 133.4, 132.4, 132.2, 132.0, 131.6, 130.7, 129.6, 129.5, 129.0, 128.9, 128.7, 128.6, 128.4, 128.2, 128.1, 127.9, 127.5, 126.6, 32.0. ^³¹P NMR (CD₂Cl₂): δ = 72.6 (s, J _P-Se = 326 Hz, J _P=Se = 802 Hz), 72.1 (s, J _P-Se = 336 Hz, J _P=Se = 784 Hz), 55.6 (s, J _P-Se = 383 Hz, J _P=Se = 770 Hz), 55.5 (s, J _P-Se = 383 Hz, J _P=Se = 767 Hz). MS (CI⁺): m/z = 385 [M + H]⁺. HRMS (CI⁺): m/z [M + H]⁺ calcd for C₁₅H₁₄PSe₂: 384.9160; found: 384.9159.
Compound 10: greyish yellow solid (230 mg) in 56% isolated yield. ^³¹P NMR spectrum revealed a pair of stereoisomers in ca. 1:2 intensity ratio. IR (KBr): 1597 (m, C=C), 1490 (s), 1460 (s), 1434 (m), 1244(vs), 1026 (m), 750 (s) cm^-¹. ^¹H NMR (CD₂Cl₂): δ = 7.02-8.20 (m, 2 × 6 H, thienyl-H + ArH), 6.83-6.99 (m, 2 × 3 H, thienyl-H), 6.37-6.51 (m, 2 × 1 H, =CH), 5.38-5.44 (m, 2 × 1 H, PCH), 3.87 (s, 3 H, OMe), 3.80 (s, 3 H, OMe), 3.29-3.45 (m, 2 × 1 H, SeCH). ^¹³C NMR (CD₂Cl₂): δ = 157.4, 156.5, 148.0, 146.0, 133.7, 133.6, 132.0, 131.9, 131.7, 131.5, 129.7, 129.4, 129.3, 129.2, 129.1, 128.5, 128.3, 128.0, 127.9, 127.4, 127.3, 127.2, 127.0, 58.1, 57.6, 55.6, 55.5. ^³¹P NMR (CD₂Cl₂): δ = 71.9 (s, J _P-Se = 322 Hz, J _P=Se = 798 Hz), 75.1 (s, J _P-Se = 315 Hz, J _P=Se = 782 Hz). ⁷⁷Se NMR (CD₂Cl₂): δ = 410.8 (d, J _P-Se = 322 Hz), 381.6 (d, J _P-Se = 315 Hz), -91.4 (d, J _P=Se = 782 Hz), -183.8 (d, J _P=Se = 798 Hz). MS (CI⁺): m/z = 415 [M + H]⁺. HRMS (CI⁺): m/z [M + H]⁺ calcd for C₁₆H₁₆OPSe₂: 414.9265; found: 414.9264.

<A NAME="RB72411TX-25">25</A> Sheldrick GM. SHELXL97. Acta Crystallogr., Sect A 2008, A64: 112