Preparation of various carboxylic acid esters from bulky alcohols and carboxylic acids by a new type oxidation-reduction condensation using 2,6-dimethyl-1,4-benzoquinone

A new-type oxidation-reduction condensation by using 2,6dimethyl-1,4-benzoquinone (DMBQ), carboxylic acids and in situ formed alkoxydiphenylphosphines (1) including the bulky alkoxy group-substituted ones proceeded smoothly to afford the corresponding carboxylic acid esters in good to high yields. Alkoxydiphenylphosphines were formed in situ by treating either N,N-dimethylaminodiphenylphosphine (Ph2PNMe2) with primary or secondary alcohols or chlorodiphenylphosphine with the lithium salts of primary, secondary and tertiary alcohols.