An enantiospecific synthesis of (+)-demethoxyerythratidinone from (S)-malic acid: key observations concerning the diastereocontrol in malic acid-derived N-acyliminium ion cyclisations
摘要:
The stereochemical outcome of N-acyliminium ion mediated cyclisations of malic acid derived lactams depend upon the nature of the protecting group on the lactam secondary alcohol, and also on the nature of the substituent at the reacting electrophilic centre. The origins of an unusual syn-selective cyclisation of a TIPS protected lactam are discussed, and the cyclisation is employed as the key step in an asymmetric synthesis of 3-demethoxyerythratidinone (4). (c) 2007 Elsevier Ltd. All rights reserved.