Development of method for preparing N-tosyliminiums and its application into synthesis of homoallylic amines

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 09640710
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: 物質変換
• Research Institution: Sophia University
• Principal Investigator: MASUYAMA Yoshiro Sophia University, Science and Technology, Lecturer, 理工学部, 講師 (30138375)
• Project Period (FY): 1997 – 1998
• Keywords: imine-allylation / homoallylamines / N-tosyliminiums / tin (II) chloride / N-chlorosuccinimide / imine-acetonylation / diastereoselectivity / regioselectivity

Research Abstract

Novel method for preparing N-tosyliminiums from aldehydes and tosylamide with N-chiorosuccinimide and tin(II) chloride was developed and was applied into synthesis of amine derivatives via addition of nucleophiles to the iminiums.
1. Synthesis of homoallylic amines by addition of allyltrimethylsilane (imine-allylation) : Various homoallylic amines were obtained in high yields by the use of aliphatic aldehydes, alpha, beta-unsaturated aldehydes, aromatic aldehydes bearing electron-donating or electron-withdrawing groups, and ketones at 5*10* in dichioromethane.
2. Diastereoselective imine-allylation by 2-butenyltrimethylsilane : Addition of 2- butenyltrimethylsilane produced anti 1-substituted 2-methylbut-3-enylamines regioselectively (=100% gamma) and diastereoselectively (>90% anti).
3. Imine-acetonylation by isopropenyl acetate : Isopropenyl acetate caused acetonylation of N- tosyliminiums under the same conditions as those of allylation described above to produce 1-(N-tosylamino)butan-3 -ones.
4. Reaction of Grignard reagents : Formation of N-tosyliminiums in refluxing TI-IF followed by addition of 5 equimolar amounts of phenylmagnesium bromide produced N-tosyldiphenylmethylamine in 50% yield. Allyl, vinyl, and alkylmagnesium halides also reacted with N-tosyliminiums to afford the corresponding amines. Consumed by the abstraction of iminium proton and the reaction with dichiorotin oxide, excess Grignard reagents needed in this method. Thus, the treatment of N-tosyliminiums with bases followed by the extraction of the resulting solution with ether reduced the quantity of Grignard reagents from 5 to 1.5 equimolar amounts.
5. syn-Diastereoselective imine-allylation by 2-butenylmagnesium chloride : Addition of 2-butenylmagnesium chloride after the treatment with bases followed by the extraction with ether led to syn-diastereoselection, in contrast to the addition of 2-butenyltrimethylsilane.