Cyclization of functionalized ketene-N,S-acetals to substituted pyrroles: applications in the synthesis of marine pyrrole alkaloids
摘要:
alpha-Oxoketene-N,S-acetals, prepared by the reaction of alkyl glycinates with beta-oxodithiocarboxylates followed by alkylation, underwent cyclization in the presence of the Vilsmeier reagent to afford alkyl 3-aryl-4-formyl-5-(alkylsulfanyl)-1H-pyrrole-2-carboxylates in excellent yields. When the reaction was extended to beta-oxodithiocarboxylates derived from deoxyanision. 3,4-diarylpyrrole-2-carboxylates, the key intermediates in the synthesis of lukianol A and lamellarin Q were formed. (C) 2004 Elsevier Ltd. All rights reserved.
An efficient synthesis of highly substituted pyrroles from β-oxodithiocarboxylates
摘要:
alpha-Oxoketene-N,S-acetals, prepared by the reaction of alkyl glycinate hydrochlorides with beta-oxodithiocarboxylates followed by alkylation, underwent cyclization in presence of chloromethyleneiminium salt derived from POCl3/DMF to afford alkyl-3-aryl-4-formyl-5-(alkylsulfanyl)-1H-pyrrole-2-carboxylates in excellent yields. Alkyl-3-aryl-5-(alkylsulfanyl)-1H-pyrrole-2-carboxylates were formed in moderate yields when the same N,S-acetals were treated with DBU. (c) 2005 Elsevier Ltd. All rights reserved.