Synthesis of chiral primary amines: diastereoselective alkylation of N-[(1E)-alkylidene]-3,5-bis[(1S)-1-methoxyethyl]-4H-1,2,4-triazol-4-amines and N4–Nexocyclic bond cleavage in the resulting 1,2,4-triazol-4-alkylamines
摘要:
Enantiomerically pure 3,5-bis[(1S)-1-methoxyethyl]-4H-1,2,4-triazol-4-amine 14a and 3,5-bis[(1S)-1-ethoxyethyl]-4H-1,2,4-triazol-4-amine 14b were used as chiral auxiliaries to obtain enantiomerically enriched alpha-aminoacetals, primary alkyl and arylalkyl amines (ee ranging from 40% to 90%). The different stages of the process were imine formation from the corresponding aldehydes, diastereoselective addition of a Grignard reagent, quaternization of the triazole auxiliary and cleavage of the N-4-N-exocylic bond by LiBH4. The mechanism of the cleavage of the N-4-N-exocyclic bond is supported by the use of deuterated metal hydride. The absolute configurations of the new stereogenic centres were established by X-ray analyses of the enantiomerically pure stereomers isolated by semi-preparative liquid chromatography on a chiral support. (C) 2008 Elsevier Ltd. All rights reserved.
作者:Giovanni Muncipinto、Philip N. Moquist、Stuart L. Schreiber、Scott E. Schaus
DOI:10.1002/anie.201103271
日期:2011.8.22
Multicomponent Petasisreactions: The first diastereoselectivePetasisreaction catalyzed by chiral biphenols that enables the synthesis of syn and anti β‐amino alcohols in pure form has been developed. The reaction exploits a multicomponent approach that involves boronates, α‐hydroxy aldehydes, and amines (see scheme).