An efficient approach to asymmetric synthesis of dipeptide β-turn mimetics: indolizidinone amino acids
摘要:
Azabicyclo[X.Y.0] alkane amino acids are rigid dipeptide P-turn mimetics with great potential applications for drug discovery. The lack of efficient methods to synthesize these compounds is a major bottleneck in this field. Herein we report an efficient approach to the enantiopure synthesis of (3S,6S,9S) and (3R,6R,9R) methyl 2-oxo-3-[N-(Boc/Cbz)amino]-1-azabicyclo[4,3,0]nonane-9-carboxylates 1. In this approach, the key intermediates 5a and 5b with different stereochemical configurations were efficiently constructed from the same precursor in high stereoselectivity via asymmetric hydrogenations using (S,S) or (R,R) Et-DUPHOS, Rh(I)-based catalysts. The process, starting from inexpensive diethyl 1,3-acetonedicarboxylate 2, can allow for the practical synthesis of this class of compounds. (C) 2001 Elsevier Science Ltd. All rights reserved.
The total synthesis of gelsedilam, which features a highly diastereoselective thiol conjugate addition–intramolecular aldol reaction to install the strained and caged [3.2.2] bridged ring system and highly efficient NiCl2/NaBH4‐mediated four‐step transformation in one‐pot to construct its five‐membered lactam ring is reported. The synthesis requires only 18 linear stepsfrom the known compounds, providing