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endo ‐Selective Intramolecular Pauson–Khand Reactions of γ ‐Oxygenated‐ α , β ‐unsaturated Phenylsulfones
Author(s) -
Adrio Javier,
Rodríguez Rivero Marta,
Carretero Juan C.
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010601)7:11<2435::aid-chem24350>3.0.co;2-o
Subject(s) - chemistry , pauson–khand reaction , intramolecular force , stereoselectivity , aldehyde , allylic rearrangement , amine gas treating , ketone , bicyclic molecule , selectivity , medicinal chemistry , organic chemistry , catalysis
A wide variety of 1,6‐enynes and 1,7‐enynes incorporating γ ‐oxygenated‐ α , β ‐unsaturated phenylsulfone moieties have readily been prepared by piperidine‐promoted condensation of the corresponding alkynyl aldehyde with phenylsulfonyl‐( p ‐tolylsulfinyl)methane and further protection of the hydroxyl group. Despite the enduring claim concerning the unsuitability of electronically deficient olefins in Pauson–Khand reactions, we report that these 1‐sulfonylated enynes are excellent substrates in intramolecular Pauson–Khand reactions under both thermal and amine N ‐oxide‐promoted conditions. Moreover, in contrast with the usual exo ‐selective Pauson–Khand cyclization of allylic substituted enynes, the reactions of these 1‐sulfonylated‐3‐oxygenated enynes occur with a moderate or high endo selectivity. The evaluation of the chemical and stereochemical scope of the process in comparison with the Pauson–Khand cyclization of non‐sulfonylated enynes, its application to the stereoselective preparation of optically pure C6‐substituted bicyclo[3.3.0]oct‐1‐en‐3‐ones, and the interpretation of the stereochemical outcome are also discussed.