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Formaldehyde SAMP‐Hydrazone as a Neutral Formyl Anion Equivalent: Asymmetric Synthesis of Substituted β‐Formyl δ‐Lactones and Furofuran Lactones
Author(s) -
Enders Dieter,
Vázquez Juan,
Raabe Gerhard
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(200003)2000:6<893::aid-ejoc893>3.0.co;2-u
Subject(s) - chemistry , ozonolysis , hydrazone , formaldehyde , lactone , stereochemistry , domino , aldehyde , pyran , hemiacetal , hydrolysis , alkylation , medicinal chemistry , organic chemistry , catalysis
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‐2 H ‐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.