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Asymmetric 1,6‐Induction in Hetero‐Diels–Alder Reactions of Chiral Oxabutadienes for a De Novo Synthesis of Enantiomerically Pure Carbohydrates: Lewis Acid Dependent Reversal of Facial Selectivity
Author(s) -
Tietze Lutz F.,
Schneider Christoph,
Montenbruck Andrea
Publication year - 1994
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199409801
Subject(s) - selectivity , lewis acids and bases , chemistry , asymmetric induction , enol ether , diels–alder reaction , chiral lewis acid , enol , ether , organic chemistry , enantioselective synthesis , stereochemistry , catalysis
Excellent endo/exo selectivity and very good induced diastereoselectivity are achieved by hetero‐Diels‐Alder reactions of oxabutadienes such as 1 , accessible from chiral oxazolidinones, with the enol ether 2 in the presence of Lewis acids. The facial selectivity can be reversed by varying the Lewis acid. The endo product is formed almost exclusively from 1 and 2 with Me 2 AlCl as promotor. In contrast, the other endo product 4 predominates with trimethylsilyltriflate (TMS‐OTf) as initiator.