No abstract

No abstract

Aliphatic and aromatic methyl ethers have been easily cleaved on treatment with a hard acid, aluminum halide, and a soft nucleophile, EtSH, to give parent alcohols and phenols, respectively. With compounds possessing both aliphatic ,and aromatic methyl ether groups, simultaneous demethylation of both types of ethers occurred. The ethereal crubon-oxygen bond in compounds possessing both ether and ester groups was selectively cleaved under mild conditions by using dichloromethane as a cosolvent. Acetoxyl and N-acetyl groups were shown to be stable to this reagent system, except for easy hydrolysis of aromatic acetoxyl groups under conditions of workup after the reaction.

We discuss a new principle, memory of chirality, which was recently introduced in the field of asymmetric synthesis. Memory of chirality is a phenomenon in which the chirality of the starting material is preserved in a reactive intermediate for a limited time. Examples are discussed, including the enantioselective alkylation of a ketone and amino acid derivatives.