An enantiospecific synthesis of (+)-demethoxyerythratidinone from (S)-malic acid: key observations concerning the diastereocontrol in malic acid-derived N-acyliminium ion cyclisations
作者:Fengzhi Zhang、Nigel S. Simpkins、Claire Wilson
DOI:10.1016/j.tetlet.2007.06.111
日期:2007.8
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.
New approaches for the synthesis of erythrinan alkaloids
作者:Fengzhi Zhang、Nigel S. Simpkins、Alexander J. Blake
DOI:10.1039/b900189a
日期:——
A concise asymmetric total synthesis of (+)-erysotramidine is described, using chiral base desymmetrisation of a meso-imide, N-acyliminium addition, retro-Diels–Alder cycloaddition and radical cyclisation as the key steps. A related route, starting from a cyclobutene-fused imide, was explored, and established a novel construction of the Erythrina alkaloid skeleton using a key ring-opening/ring-closing
Asymmetric synthesis of both enantiomers of novel tetracyclic heterocycle, furo[3′,2′:2,3]pyrrolo[2,1-a]isoquinoline derivative via a diastereoselective N-acyliminium ion cyclization
作者:Jae Yeol Lee、Yong Sup Lee、Bong Young Chung、Hokoon Park
DOI:10.1016/s0040-4020(96)01179-9
日期:1997.2
An efficientsynthesis of both enantiomers of tetracyclic isoquinoline derivative (−)-2 and (+)-2 was accomplished starting from L-malic acid and L-tartaric acid, respectively. The key step is the stereoselective introduction of quaternary carbon-center in ring juncture using a diastereoselectiveN-acyliminiumioncyclization of chiral enamides (1, 3).