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Stereoselective Synthesis of 2 H ‐Chromans by Reductive Deoxygenation of Differently Substituted 2‐Sulfinylmethylchroman‐2‐ols
Author(s) -
HernándezTorres Gloria,
Carreño M. Carmen,
Urbano Antonio,
Colobert Françoise
Publication year - 2011
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/ejoc.201100436
Subject(s) - deoxygenation , chemistry , stereoselectivity , yield (engineering) , enantiopure drug , sulfoxide , medicinal chemistry , stereochemistry , organic chemistry , catalysis , enantioselective synthesis , materials science , metallurgy
Good‐to‐excellent diastereoselectivies have been achieved in the synthesis of 2 H ‐chromans by Et 3 SiH/TMSOTf reductive deoxygenation of differently substituted 2‐sulfinylmethylchroman‐2‐ols and their methyl ketals. The influence of both electron‐donating and ‐withdrawing substituents on the sulfoxide and on the aromatic dihydobenzopyran core has been studied. SOR 1 electron‐donating groups (R 1 = p MeOPh and 2‐MeO‐1‐naphthyl) led to a competitive reaction in which the sulfoxide was reduced, thus lowering the yield of the sulfinyl 2 H ‐chromans. The method allows the presence of different groups on the aromatic dihydrobenzopyran unit. The best results in terms of yield and diastereoselectivity were obtained with 2‐[( p ‐tolylsulfinyl)methyl]chroman‐2‐ols. All the results are explained on mechanistic grounds. Synthetic transformations of the enantiopure 2 H ‐chroman ( S , R S )‐ 21 are reported.