Interesting product formation during <i>O</i>-alkylation and subsequent rearrangement of two building blocks of dibromotyrosine based natural products

Abstract

1460-1466The O-alkylation (allylation/propargylation) of 3,5-dibromo-4-hydroxybenzaldehyde 1 and the corresponding acetophenone 2 results in the formation of aryl-aryl coupled product by loss of formyl groups, aryl-aryl ether and aryloxy acetone in addition to the expected O- allyl/ propargyl ethers. While the thermal Claisen rearrangement of allyl ethers 1 and 2 furnishes the C-allyl products by loss of bromine, the propargyl ether 7 surprisingly resisted rearrangement and underwent oxidation to yield the corresponding carboxylic acid