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Formylation of activated arenes by phenyl formate: implications for the mechanism of the Fries rearrangement of aryl formates
Author(s) -
Bagno Alessandro,
Kantlehner Willi,
Saielli Giacomo
Publication year - 2008
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.1356
Subject(s) - chemistry , fries rearrangement , salicylaldehyde , formate , moiety , aryl , regioselectivity , medicinal chemistry , formylation , phenol , organic chemistry , stereochemistry , catalysis , schiff base , alkyl
Abstract We present an NMR and DFT investigation of the reaction of phenyl formate with 3‐methoxyphenol and 3,5‐dimethoxyphenol with excess BCl 3 . The products obtained (3‐methoxy‐ and 3,5‐dimethoxy‐salicylaldehyde, respectively) are the same as those resulting from the Fries rearrangement of 3‐methoxy‐ and 3,5‐dimethoxy‐phenyl formate. These results represent a novel regioselective synthetic route to aromatic aldehydes, using phenyl formate as a source of formylating agent. They also unambiguously prove that the Fries rearrangement of aryl formates (that we recently investigated in J. Org. Chem . 71 , 9331–9340, 2006) is intermolecular: the intermediate formyl chloride is released in situ and, in turn, it formylates the intermediate dichloroborate ester of 3‐methoxy‐ and 3,5‐dimethoxy‐phenol in a second independent step. The BCl 2 moiety bound to the aryl oxygen of the substituted phenol interacts with the formyl chloride strongly favouring the ortho substitution. Copyright © 2008 John Wiley & Sons, Ltd.