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A Diastereoselective Route to trans ‐2‐Aryl‐2,3‐dihydrobenzofurans through Sequential Cross‐Metathesis/Isomerization/Allylboration Reactions: Synthesis of Bioactive Neolignans
Author(s) -
Hemelaere Rémy,
Carreaux François,
Carboni Bertrand
Publication year - 2015
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.201500019
Subject(s) - isomerization , chemistry , metathesis , intramolecular force , aryl , enantioselective synthesis , substituent , stereochemistry , stereoselectivity , organic chemistry , combinatorial chemistry , catalysis , alkyl , polymerization , polymer
A new highly diastereoselective synthetic route to trans ‐2,3‐dihydrobenzofuran systems, in particular those bearing an aryl substituent at the C2 position, is described. The cornerstone of our strategy is the implementation of a cross‐metathesis/isomerization/allylboration sequence starting from 2‐allyl‐substituted phenols and aldehydes. After an intramolecular Mitsunobu cyclization step, the anti ‐homoallylic alcohols allow the synthesis of the desired skeleton in a stereoselective fashion. As an illustration, we used this strategy for the preparation of the dihydrodehydrodiconiferyl alcohol ( 1a ), a natural dihydrobenzofuran neolignan, as well as for a formal synthesis of its O ‐demethylated derivative 1b . An enantioselective version of this approach employing a chiral phosphoric acid in the allylboration step is also studied.