The first enantioselective synthesis of (S)-5-bromo-3-(1-methyl-2-pyrrolidinyl)pyridine: a key intermediate for the preparation of SIB-1508Y
摘要:
The first enantioselective synthesis of (S)-5-bromo-3-(1-methyl-2-pyrrodidinyl)pyridine is described via intramolecular hydroboration-cycloalkylation of an azido-olefin intermediate. The chiral homoallylic alcohol was efficiently synthesized by enantioselective reduction of the corresponding ketone using (+)-diisopinocamphenylchloroborane as the key reaction. The total synthesis of (S)-SIB-1508Y was achieved with an enantiomeric excess (e.e.) of 94% in ten steps and in 18% overall yield from the commercially available 5-bromo-3-pyridinecarboxylic acid. (C) 2001 Elsevier Science Ltd. Ali rights reserved.
Enantioselective reduction of heteroaromatic β,γ-unsaturated ketones was found to be an efficient and convenient alternative to the allylboration of corresponding aldehydes. This new method was used for the formal asymmetric synthesis of SIB-1508Y 2.
The first enantioselective synthesis of (S)-5-bromo-3-(1-methyl-2-pyrrodidinyl)pyridine is described via intramolecular hydroboration-cycloalkylation of an azido-olefin intermediate. The chiral homoallylic alcohol was efficiently synthesized by enantioselective reduction of the corresponding ketone using (+)-diisopinocamphenylchloroborane as the key reaction. The total synthesis of (S)-SIB-1508Y was achieved with an enantiomeric excess (e.e.) of 94% in ten steps and in 18% overall yield from the commercially available 5-bromo-3-pyridinecarboxylic acid. (C) 2001 Elsevier Science Ltd. Ali rights reserved.