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A simple two steps ytterbium triflate‐catalysed preparation of 2,2‐dimethyl‐2 h ‐chromenes from salicylaldehydes and 2‐methylpropene
Author(s) -
Prado Soizic,
Janin Yves L.,
Bost PierreEtienne
Publication year - 2006
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570430626
Subject(s) - chemistry , trifluoromethanesulfonate , salicylaldehyde , ytterbium , catalysis , medicinal chemistry , phenol , organic chemistry , stereochemistry , schiff base , physics , optoelectronics , doping
The preparation of various 2,2‐dimethyl‐2 H ‐chromenes was achieved in two steps via an ytterbium triflate‐catalysed reaction between salicylaldehydes, trimethylorthoformate and 2‐methylpropene. From salicylaldehyde, two reaction products were characterised: 4‐methoxy‐2,2‐dimethylchroman and 2‐(1,3‐dimethoxy‐3‐methylbutyl)phenol. The former compound probably results from a Lewis acid‐catalysed [2+4] cycloaddition between the intermediate quinonemethide and 2‐methylpropene whereas the latter may occur via a reaction related to a carbonyl‐ene reaction between the quinonemethide and 2‐methylpropene. Both compounds were subjected to a catalytic acidic treatment leading to 2,2‐dimethyl‐2 H ‐chromene. Starting from various salicylaldehydes, the scope of this method was investigated.