Convenient Method for N-Debenzylation of Tertiary Amines

References

• Harting , H. H. and Simonoff , R. 1953 . Org. Reactions , 7 : 263
   Google Scholar
• Olofson , R. A. , Schnur , R. C. , Bunes , L. and Pepe , J. P. 1977 . Tetrahedron Lett. 1567
   Google Scholar
• Olofson , R. A. , Martz , J. T. , Senel , J. P. , Piteau , M. and Malfoot , T. 1984 . J. Org. Chem. , 49 : 2081
   Web of Science ®Google Scholar
• Narayana , C. and Periasamy , M. 1987 . J. Chem. Soc., Chem. Commun. , : 1857
   Google Scholar
• Kanth , J. V. B. and Periasamy , M. 1990 . J. Chem. Soc., Chem. Commun. , : 1145
   Google Scholar
• Representative procedure for debenzylation: To a solution of diasteriomerically pure (+)N-α-methylbenzyl-3,4-diphenyl pyrrolidine (1.63g, 5 mmol) in dry dichloroethane (20 ml), ethyl chloroformate (0.66g, 6 mmol) was added and the mixture was refluxed for 4h. The solvent was removed under reduced pressure to yield essentially pure N-ethyl carbamate derivative. Yield: 1.4g, (95%). IR(neat): 1680, 1600 cm−1. 1H NMR (100 MHz, CDCl3): δ ppm 1.2 (t, 3H), 3.4–4.2 (m, 8H), 7.1 (m, 10H). 13C NMR (25.0 MHz, CDCl3): δ ppm 14.6, 50.4, 51.3, 53.1, 60.9, 126.9, 127.4, 128.5, 139.2, 154.9.
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• Tomioka , K. , Nakagima , M. and Koga , K. 1987 . Chemistry Lett. 65.N, N-Diethylaniline-BI3 complex was prepared following the reported procedure,8 through the addition of I2(7.5 mmol) in benzene to N, N-diethylaniline borane complex (5 mmol) and stirring the mixture at 25°C for 8h. To this, the N-ethyl carbamate of 3,4-diphenylpyrrolidine(1.47g, 5 mmol) in benzene (20 ml) was added slowly during 15 min. under nitrogen and the mixture was stirred further for 8h. The reaction was quenched with water and neutralised using 3N NaOH solution. The organic layer was separated and washed with NaOH solution (3N, 3x10 ml), brine and dried over anhydrous MgSO4. Evaporation of the solvent afforded crude product which was separated from N, N-diethylaniline by column chromatography on alumina (neutral) using hexane : ethyl acetate/80:20. Yield: 0.95g, (89%). IR(neat): 3345, 1600 cm−1. 1H NMR(100 MHz, CDCl3): 2.3 (s, 1H), 2.8–3.4 (m, 6H), 6.9 (m, 10H). [α]D 20 = +222°(Cl, CHCl3). Lit. [α]D 20 = -226°(CHCl3)
   Google Scholar
• Hall , D. M. and Turner , E. E. 1951 . J. Chem. Soc. Part 2 , : 3072
   Google Scholar
• Reddy , Ch. K. and Periasamy , M. 1990 . Tetrahedron Lett. 1919
   Google Scholar
• Narayana , C. , Padmanabhan , S. and Kabalka , G. W. 1990 . Tetrahedron Lett. 6977
   Google Scholar
• Narayana , C. , Padmanabhan , S. and Kabalka , G. W. 1991 . Synlett 125
   Google Scholar
• Narayana , C. , Reddy , N. K. and Kabalka , G. W. 1991 . Tetrahedron Lett. 6855
   Google Scholar
• Suzuki , T. , Uozumi , Y. and Shibasaki , M. 1991 . J. Chem. Soc., Chem. Commun. , : 1593
   Google Scholar