Formaldehyde SAMP-Hydrazone as a Neutral Formyl Anion Equivalent: Asymmetric Synthesis of Substituted β-Formyl δ-Lactones and Furofuran Lactones

• Published in: European journal of organic chemistry Vol. 2000; no. 6; pp. 893 - 901
• Main Authors: Enders, Dieter, Vázquez, Juan, Raabe, Gerhard
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 01.03.2000; WILEY‐VCH Verlag GmbH; Wiley
• Subjects: Addition reactions; Asymmetric synthesis; Chemistry; Chemistry, Organic; Domino reactions; Formyl anion equivalent; Lactones; Nucleophilic formylation; Physical Sciences; Science & Technology; Michael addition; ENANTIOSELECTIVE SYNTHESIS; DIALKYLHYDRAZONES; formyl anion equivalent; STEREOSELECTIVE SYNTHESES; NEOLIGNANS; nucleophilic formylation; lactones; asymmetric synthesis; ALPHA-HYDROXY ALDEHYDES; domino reactions; RADICAL CYCLIZATION; CYANIDE EQUIVALENT; LIGNANS; CONJUGATED ENONES
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/(SICI)1099-0690(200003)2000:6<893::AID-EJOC893>3.0.CO;2-U

An efficient asymmetric synthesis of α‐substituted β‐formyl δ‐lactones 5 (de ≥ 98%, ee = 80‐95%) and 4‐substituted furofuran lactones 6 (de ≥ 98%, ee = 80‐>98%) in acceptable overall yields is reported. Key steps of the new procedure are an asymmetric Michael addition of formaldehyde SAMP‐hydrazone (1) to 5,6‐dihydro‐2H‐pyran‐2‐one (2) under neutral conditions, followed by trans‐selective α‐alkylation and subsequent cleavage of the auxiliary by ozonolysis or a hydrolytic domino reaction protocol, respectively. The absolute configurations given for the title compounds are based on three X‐ray structure analyses and NOE measurements.