601488-19-1Relevant articles and documents
Domino aza-Claisen/Mannich cyclization reaction from a chiral α-alkoxy enamine or sequential alkylation of an α-alkoxy ester enolate or nitrile anion, followed by an intramolecular Wittig reaction: Two (3+2) annulation routes to homochiral 4-alkyl-4-hydroxy-2-cyclopentenone synthesis
Kuhn, Cyrille,Skaltsounis, Leandros,Monneret, Claude,Florent, Jean-Claude
, p. 2585 - 2595 (2003)
A study on the enantioselective synthesis of 4-alkyl-4-hydroxyalkylidene-cyclopentenone prostaglandins is reported. Two (3+2) annulation processes allow the synthesis of homochiral 4-alkyl-4-hydroxy-2-cyclopentenones 4-5, 10-11, and 17. The first process involves a domino aza-Claisen/Mannich cyclization reaction, resulting from the alkylation of an α-alkoxy-enamine, derived from chiral α-alkoxy aldehydes 1, 9, or 16 with 3-iodo-2-(methoxymethoxy)prop-1-ene (3) as the acetonyl equivalent. The second process is based on the sequential alkylation of esters 21, 39, or nitrile 20 with acetonyl equivalents 3 or 25, followed by an intramolecular Wittig reaction. As an application, the synthesis of the naturally occurring alkylidene-cyclopentenone prostaglandin clavulone II from the spiro[cyclopentene-furan]one 5 and the formal total synthesis of (+/-)-untenone 19 has been carried out. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.