A Rapid and Efficient Cleavage of Organic Disulfides to Mercaptans Using ZrCl₄/NaBH₄

References

• Bulman Page , P. C. , Wilkes , R. D. and Reynolds , D. Alkyl Chalcogenides: Sulphur Based Functional Groups - “Comprehensive Organic Functional Group Transformations” Edited by: Katritzky , A. R. , Meth-Cohn , O. and Rees , C. W. Vol. 2 , 113 in Chapter 2.03
   Google Scholar
• Patai , S. 1974 . “The Chemistry of Thiol Group” , London : John Wiley & Sons .
   Google Scholar
• Bordwell , F. G. and Andersen , H. M. 1953 . J. Am. Chem. Soc. , 75 : 6019
   Web of Science ®Google Scholar
• Gunther , W. H. H. 1966 . J. Org. Chem. , 31 : 1202
   Web of Science ®Google Scholar
• Kong , F. and Zhou , X. 1989 . Synth. Commun. , : 3143
   Google Scholar
• Lees , W. J. , Singh , R. and Whitesides , G. M. 1991 . J. Org. Chem. , 56 : 7328
   Google Scholar
• Brown , H. C. , Nazer , B. and Cha , J. S. 1984 . Synthesis , : 498
   Google Scholar
• Kolthoff , I. M. , May , D. R. , Morgan , P. , Laitinen , H. A. and O'Brien , A. S. 1946 . Anal. Chem. , 18 : 442
   Google Scholar
• Kipnis , F. , Levy , I. and Omfelt , J. 1949 . J. Am. Chem. Soc. , 71 : 2270
   Google Scholar
• Humphrey , Du. , Audrieth , L. F. and Loring , H. S. 1930 . J. Am. Chem. Soc. , 52 : 4500
   Google Scholar
• Humphrey , R. E. and Potter , J. L. 1965 . Anal. Chem. , 37 : 164
   Web of Science ®Google Scholar
• Overmann , L. E. , Smoot , J. and Overmann , J. D. 1974 . Synthesis , : 59
   Google Scholar
• Akers , H. A. , Vang , M. C. and Updike , T. D. 1987 . Can. J. Chem. , 65 : 1364
   Google Scholar
• Sridhar , M. , Vadivel , S. K. and Bhalerao , U. T. 1997 . Synth. Commun. , 27 ( 8 ) : 1347
   Web of Science ®Google Scholar
• Vidyasagar Reddy , G. , Venkat Rao , G. and Iyengar , D. S. Synth. Commun. (in press) ,
   Google Scholar
• Arnold , R. C. , Lien , A. P. and Alm , R. M. 1950 . J. Am. Chem. Soc. , 72 : 638
   Google Scholar
• Djerassi , C. and Grossman , J. 1957 . J. Am. Chem. Soc. , 79 : 2553
   Web of Science ®Google Scholar
• Brown , H. C. , Weissman , P. M. and Yoon , N. M. 1966 . J. Am. Chem. Soc. , 88 : 1458
   Web of Science ®Google Scholar
• Purushothama Chary , K. , Santosh Laxmi , Y. R. and Iyengar , D. S. 1999 . Synth. Commun. , 29 ( 8 ) : 1257
   Web of Science ®Google Scholar
• Santosh Laxmi , Y. R. and Iyengar , D. S. 1997 . Synth. Commun. , 27 : 1731
   Web of Science ®Google Scholar
• Purushothama Chary , K. , Hari Mohan , G. and Iyengar , D. S. 1999 . Chem. Lett , 11 : 1223
   Web of Science ®Google Scholar
• Typical Experimental Procedure: Into a two necked round bottom flask equipped with magnetic bead and nitrogen balloon adopter was placed ZrCl4 (0.189g, 0.81mmol), dry THF (5 ml) was syringed into the flask. Immediate formation of reddish brown solution was observed. The contents were cooled to 0 °C, NaBH4 (0.123g, 3.246 mmol) was added in portion to the above solution. Reddish brown solution slowly turned to pale pink. To this reagent system at 0 °C was added p-tolyl disulfide (entry 5)(0.2g, 0.8 mmol) in dry THF (5 ml). Contents were stirred magnetically. After completion of addition of disulfide ice cooling was removed and contents were brought to room temperature (35 °C). The progress of the reaction monitored by TLC clearly indicated the disappearance of the disulfide in 15 minutes. Contents were cooled and treated with 20% aq. HCl solution gave the separation of organic layer. THF was evaporated under vacuum, extracted into ethyl acetate (10 ml), washed with water and dried over anhydrous Na2SO4. Evaporation of the organic portion followed by silicagel column chromatography provided pure 4-methylbenzene thiol (0.191g, 95% yield), a low melting solid
   Google Scholar
• H 1 NMR analysis data of time dependent chemoselective cleavage of Nitro Disulfides to Mercaptans: Entry 13 [Analysis of the crude reaction mixture, after workup in 10 minutes] : (200 MHz H1 NMR, δ ppm, in CDCl3) [δ 3.2 (br, SH), 7.03 (m, 1H, ortho hydrogen w.r.to SH), 7.2-7.3 (m, 2H, aromatic hydrogens), 8.24 (m, 1H, ortho hydrogen w.r.to NO2) & 6.68-7.0 (m, 1H, ortho hydrogen w.r.to SH)] measurement of integration indicated a ratio of 2-Nitro-1-benzenethiol : 2-amino-1-benzenethiol as 80:20. Later the mixture was subjected to silicagel column chromatography purification, provided pure 2-Nitro-1-benzenethiol (low melting solid, m.p 58 °C, isolated yield 80%) and 2-amino-1-benzenethiol (liquid, isolated yield 20%)
   Google Scholar
• Entry 13 [Analysis of crude reaction mixture, after workup in 30 minutes] : (200 MHz H1 NMR, δ ppm, in CDCl3) [δ 3.2 (br, SH), 6.6-6.7 (m, 1H, ortho hydrogen w.r.to SH), 6.8-7.0 (m, 1H, ortho hydrogen w.r.to NH2) 7.0-7.1 (m, 2H, aromatic) & 8.2 (m, 1H, ortho hydrogen w.r.to NO2)] measurement of integration indicated a ratio of 2-Nitro-1-benzenethiol : 2-amino-1-benzenethiol as 10:90. Later the mixture was subjected to silicagel column chromatography purification, provided pure 2-Nitro-1-benzenethiol (low melting solid, m.p 58 °C, isolated yield 10%) and 2-amino-1-benzenethiol (liquid, isolated yield 90%)
   Google Scholar
• Ambrogi , V. and Grandolini , G. 1987 . Synthesis , : 724
   Web of Science ®Google Scholar