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Stereocontrolled Syntheses of Polysubstituted 2,3‐Dihydro‐4 H ‐pyran‐4‐ones by cyclocondensation of β‐ acyloxy‐ketones
Author(s) -
Oppolzer Wolfgang,
Rodriguez Inés
Publication year - 1993
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19930760315
Subject(s) - chemistry , pyran , intramolecular force , stereoselectivity , ketone , stereochemistry , bicyclic molecule , organic chemistry , catalysis
syn ‐β‐Acyloxy‐ketones 6 and an anti ‐β‐acyloxy‐ketone 17 undergo smooth intramolecular enolate/ester condensations 6 → 18 and 17 → 19 when treated with TiCl 4 /EtN(i‐Pr) 2 . Thus, tri‐ and tetrasubstituted cis ‐ or trans ‐2,3‐dihydro‐4 H ‐pyran‐4‐ones are easily prepared in a stereoselective manner.