References and Notes
See reviews:
<A NAME="RD12507ST-1A">1a</A>
Wood JL. In
Organic Reactions
Vol. 3:
Wiley;
New York:
1967.
p.240-266
<A NAME="RD12507ST-1B">1b</A>
Kelly TR.
Kim MH.
Certis ADM.
J. Org. Chem.
1993,
58:
5855
<A NAME="RD12507ST-2A">2a</A>
Toste FD.
Laronde F.
Still WJ.
Tetrahedron Lett.
1995,
36:
2949
<A NAME="RD12507ST-2B">2b</A>
Grant MS.
Snyder HR.
J. Am. Chem. Soc.
1960,
82:
2742
<A NAME="RD12507ST-3">3</A>
Guy RG. In The Chemistry of Cyanates and Their Thio Derivatives
Part 2:
Patai S.
John Wiley and Sons;
New York:
1977.
Chap. 18.
p.819-886
<A NAME="RD12507ST-4A">4a</A>
Taylor EC.
Kienzle F.
Synthesis
1972,
38
<A NAME="RD12507ST-4B">4b</A>
Uemura S.
Onoe A.
Okazaki H.
Okano M.
Bull. Chem. Soc. Jpn.
1975,
48:
619
<A NAME="RD12507ST-4C">4c</A>
Kita Y.
Takada T.
Mihara S.
Whelan BA.
Tohma H.
J. Org. Chem.
1995,
60:
7144
<A NAME="RD12507ST-4D">4d</A>
Khazei A.
Alizadeh A.
Vaghei RG.
Molecules
2001,
6:
253
<A NAME="RD12507ST-5A">5a</A>
Toste FD.
Stefano VD.
Still IWJ.
Synth. Commun.
1995,
25:
1277
<A NAME="RD12507ST-5B">5b</A>
Nair V.
George TG.
Nair LG.
Panicker SB.
Tetrahedron Lett.
1999,
40:
1195
<A NAME="RD12507ST-5C">5c</A>
Chakrabarty M.
Sarkar S.
Tetrahedron Lett.
2003,
44:
8131
<A NAME="RD12507ST-5D">5d</A>
Yadav JS.
Reddy SBV.
Shubashree S.
Sadashiv K.
Tetrahedron Lett.
2004,
45:
2951
<A NAME="RD12507ST-5E">5e</A>
Yadav JS.
Reddy BVS.
Krishna AD.
Reddy CS.
Narsaiah AV.
Synthesis
2005,
961
<A NAME="RD12507ST-5F">5f</A>
Wu G.
Liu Q.
Shen Y.
Wu W.
Wu L.
Tetrahedron Lett.
2005,
46:
5831
<A NAME="RD12507ST-6A">6a</A>
Das B.
Holla H.
Srinivas Y.
Tetrahedron Lett.
2007,
48:
61
<A NAME="RD12507ST-6B">6b</A>
Khan AT.
Ali MA.
Goswami P.
Chaudhari LH.
J. Org. Chem.
2006,
71:
8961
<A NAME="RD12507ST-6C">6c</A>
Chaudhari LH.
Synlett
2006,
1619
<A NAME="RD12507ST-6D">6d</A>
Khan AT.
Mondal E.
Ghosh S.
Islam S.
Eur. J. Org. Chem.
2004,
2002
<A NAME="RD12507ST-6E">6e</A>
Khan AT.
Mondal E.
Borah BM.
Ghosh S.
Eur. J. Org. Chem.
2003,
4113
<A NAME="RD12507ST-7A">7a</A>
Furukawa N.
Inoue T.
Aida T.
Oae S.
J. Chem. Soc., Chem. Commun.
1973,
212
<A NAME="RD12507ST-7B">7b</A>
Olah GA.
Vankar YD.
Arvanaghi M.
Surya Prakash GK.
Synthesis
1979,
720
<A NAME="RD12507ST-7C">7c</A>
Olah GA.
Arvanaghi M.
Vankar YD.
Synthesis
1979,
721
<A NAME="RD12507ST-7D">7d</A>
Chow YL.
Bakker BH.
Can. J. Chem.
1982,
60:
2268
<A NAME="RD12507ST-7E">7e</A>
Majetich G.
Hicks R.
Reister S.
J. Org. Chem.
1997,
62:
4321
<A NAME="RD12507ST-8">8</A>
Epstein IR.
Kustin K.
J. Phys. Chem.
1992,
96:
6326
<A NAME="RD12507ST-9">9</A>
Preparation of Bromodimethylsulfonium Bromide (BDMS):7a Dimethyl sulfide (3.69 mL, 50 mmol) was taken in anhyd CH2Cl2 (10 mL) into a 150-mL conical flask. Then, bromine (2.56 mL, 50 mmol) dissolved in
anhyd CH2Cl2 (10 mL) was added slowly into the above solution at ice-bath temperature over a period
of 10 min. During the addition, light orange crystals of bromodimethylsulfonium bromide
begin to separate out. After the addition of bromine was complete, the crystals of
bromodimethylsulfonium bromide were collected by filtration, washed with anhyd hexane
and dried under vacuum; yield: 8.6 g (77%); mp 80-82 °C (lit.7a 81-82 °C).
<A NAME="RD12507ST-10">10</A>
General Experimental Procedure for Thiocyanation: To a yellow suspension of BDMS (1.66 g, 7.5 mmol) and ammonium thiocyanate (1.14
g, 15 mmol) in anhyd MeCN (50 mL) the substrate (5 mmol) was added immediately in
one portion. The reaction mixture was stirred at r.t. until complete consumption of
starting material as observed by TLC. After completion of the reaction, it was quenched
with sat. solution of NaHCO3 (50 mL) and the solid residue was removed by filtration and the residue was washed
with EtOAc. The organic layer was separated, washed with H2O (50 mL), brine (50 mL) and dried over anhyd Na2SO4 and concentrated under reduced pressure to give the crude thiocyanato product. Pure
product was obtained after column chromatography (silica gel, mesh size 60-120, eluent
EtOAc-hexane, 10:90).
Caution!! Reaction generates odorous dimethyl sulfide. All operations should be carried out
in well-ventilated hood. The effluent should be treated with bleach before disposal.
Spectral Data for Thiocyanated Products
2-Methyl-4-thiocyanatophenol (1a): solid; mp 70-72 °C (lit.11 71-72 °C). 1H NMR (60 MHz, CDCl3): δ = 3.24 (s, 3 H), 6.14 (br s, 1 H), 6.64-7.25 (m, 3 H). IR (KBr): 3378, 2925,
2159 (SCN), 1597, 1495, 1275, 815 cm-1.
4-Thiocyanatophenol (2a): solid; mp 51-52 °C (lit.11 52-53 °C). 1H NMR (60 MHz, CDCl3): δ = 5.62 (br s, 1 H), 6.79 (d, J = 8.4 Hz, 2 H), 7.36 (d, J = 8.4 Hz, 2 H). IR (KBr): 3363, 3009, 2158 (SCN), 1585, 1492, 1212, 828, 756 cm-1.
1-Methoxy-4-thiocyanatobenzene (3a): solid; mp 33-34 °C (lit.12 33-34 °C). 1H NMR (60 MHz, CDCl3): δ = 3.74 (s, 3 H), 6.69 (d, J = 9.0 Hz, 2 H), 7.31 (d, J = 9.0 Hz, 2 H). IR (KBr): 2985, 2155 (SCN), 1587, 1475, 1267, 818, 712 cm-1.
1-Methoxy-4-thiocyanatonaphthalene (4a): solid; mp 104-106 °C (lit.4c 106-107 °C). 1H NMR (60 MHz, CDCl3): δ = 4.08 (s, 3 H), 6.71-6.75 (m, 1 H), 7.62-8.29 (m, 5 H). IR (KBr): 2978, 2152
(SCN), 1591, 1271, 1063, 807, 771 cm-1.
1-Methoxy-2-methyl-4-thiocyanatobenzene (5a): oil (lit.4c oil). 1H NMR (60 MHz, CDCl3): δ = 2.50 (s, 3 H), 3.91 (s, 3 H), 6.81-7.16 (m, 3 H). IR (KBr): 2990, 2153 (SCN),
1596, 1485, 1260, 880 cm-1.
4-Thiocyanatobenzenamine (6a): solid; mp 50-52 °C (lit.5f 51-52 °C). 1H NMR (60 MHz, CDCl3): δ = 3.82 (br s, 2 H), 6.67 (d, J = 8.8 Hz, 2 H), 7.33 (d, J = 8.8 Hz, 2 H). IR (KBr): 3403, 3350, 2137 (SCN), 1627, 1591, 1432, 818 cm-1.
2-Methyl-4-thiocyanatobenzenamine (7a): solid; mp 70-71 °C (lit.13 70-71 °C). 1H NMR (60 MHz, CDCl3): δ = 2.44 (s, 3 H), 3.75 (br s, 2 H), 6.43-6.62 (m, 2 H), 7.18-7.52 (m, 1 H). IR
(KBr): 3354, 3243, 2145 (SCN), 1628, 1592, 1492, 1298, 821 cm-1.
2,6-Dimethyl-4-thiocyanatobenzenamine (8a): solid; mp 85-87 °C (lit.14 87-88 °C). 1H NMR (60 MHz, CDCl3): δ = 2.44 (s, 6 H), 3.87 (br s, 2 H), 6.62 (s, 1 H), 7.22 (s, 1 H). IR (KBr): 2928,
2147 (SCN), 1615, 1592, 1460, 1288 cm-1.
N
,
N
-Dimethyl-4-thiocyanatobenzenamine (9a): solid; mp 72-74 °C (lit.5f 73-74 °C). 1H NMR (60 MHz, CDCl3): δ = 2.99 (s, 6 H), 6.76 (d, J = 9.0 Hz, 2 H), 7.51 (d, J = 9.0 Hz, 2 H). IR (KBr): 2922, 2137 (SCN), 1586, 1503, 1362, 1077, 802 cm-1.
N
-Benzyl-
N
-methyl-4-thiocyanatobenzenamine (10a): solid; mp 68-70 °C. 1H NMR (60 MHz, CDCl3): δ = 3.07 (s, 3 H), 4.57 (s, 2 H), 6.69 (d, J = 9.0 Hz, 2 H), 7.05 (s, 5 H), 7.39 (d, J = 9.0 Hz, 2 H). IR (KBr): 3014, 2144 (SCN), 1599, 1460, 1023, 824 cm-1. Anal. Calcd for C15H14N2: C, 70.83; H, 5.55; N, 11.01. Found: C, 70.85; H, 5.54; N, 10.98.
N
,
N
-Diallyl-4-thiocyanatobenzenamine (11a): oil; 1H NMR (60 MHz, CDCl3): δ = 3.78-3.97 (m, 4 H), 4.96-5.26 (m, 4 H), 5.55-6.06 (m, 2 H), 6.63 (d, J = 9.0 Hz, 2 H), 7.35 (d, J = 9.0 Hz, 2 H). IR (KBr): 3082, 2916, 2148 (SCN), 1641, 1591, 1504, 1238, 811 cm-1. Anal. Calcd for C13H14N2S: C, 67.79; H, 6.13; N, 12.16. Found: C, 67.82; H, 6.15; N, 12.18.
2-Amino-6-methoxybenzothiazole (12a): solid; mp 158-160 °C (lit.15 161-162 °C). 1H NMR (60 MHz, CDCl3): δ = 3.82 (s, 3 H), 5.05 (br s, 2 H), 6.80-7.53 (m, 3 H). IR (KBr): 3435, 3312,
1596, 1230 cm-1.
2-Amino-6-methylbenzothiazole (13a): solid; mp 130-132 °C (lit.16 131-132 °C). 1H NMR (60 MHz, CDCl3): δ = 2.23 (s, 3 H), 5.26 (br s, 2 H), 6.92-7.69 (m, 3 H). IR (KBr): 3325, 3413,
1590 cm-1.
2-Amino-6-bromobenzothiazole (14a): solid; mp 212-213 °C (lit.16 213-214 °C). 1H NMR (60 MHz, CDCl3): δ = 4.93-5.31 (br s, 2 H), 7.32-7.85 (m, 3 H). IR (KBr): 3320, 3430, 1605 cm-1.
2-Methyl-3-thiocyanato-1
H
-indole (15a): solid; mp 101-102 °C (lit.5f 102-103 °C). 1H NMR (60 MHz, CDCl3): δ = 2.50 (s, 3 H), 7.70-7.75 (m, 3 H), 7.64-7.69 (m, 1 H), 8.56 (br s, 1 H). IR
(KBr): 3323, 3061, 2152 (SCN), 1614, 1583, 1408, 1228, 741 cm-1.
2-Thiocyanato-1
H
-pyrrole (16a): oil (lit.5f oil). 1H NMR (60 MHz, CDCl3): δ = 6.26 (m, 1 H), 6.61 (m, 1 H), 6.95 (m, 1 H), 8.83 (br s, 1 H). IR (neat): 3340,
2952, 2159 (SCN), 1530, 1422, 1029, 737 cm-1.
2-Thiocyanatothiophene (17a): oil (lit.17 oil). 1H NMR (60 MHz, CDCl3): δ = 7.50-8.12 (m, 3 H). IR (neat): 3012, 2158 (SCN), 1412, 1215, 850, 728 cm-1.
<A NAME="RD12507ST-11">11</A>
Kaji A.
Nippon Kagaku Zasshi
1961,
82:
382 ; Chem. Abstr. 1962, 56, 10054h
<A NAME="RD12507ST-12">12</A>
Nelson MJ.
Pullin ADE.
J. Chem. Soc.
1960,
604
<A NAME="RD12507ST-13">13</A>
Zaboev SA.
Kudryavtzev NA.
J. Gen. Chem. USSR (Engl. Transl.)
1935,
5:
1607 ; Chem. Abstr. 1936, 30, 21824
<A NAME="RD12507ST-14">14</A>
Kissman HM.
Tarbell DS.
Williams J.
J. Am. Chem. Soc.
1953,
75:
2959
<A NAME="RD12507ST-15">15</A>
Charris J.
Monasterios M.
Dominguez J.
Infante W.
Castro ND.
Heterocycl. Commun.
2002,
8:
275
<A NAME="RD12507ST-16">16</A>
Jordan AD.
Luo C.
Reitz AB.
J. Org. Chem.
2003,
68:
8693
<A NAME="RD12507ST-17">17</A>
Karade NN.
Tiwari GB.
Shirodkar SG.
Dhoot BM.
Synth. Commun.
2005,
35:
1197