New, useful reactions of novel haloformates and related reagents

Abstract

Uses of the a-chloroalkyl chioroformates 2 obtained by the Cl - catalyzed addition of phosgene to aldehydes are reported. The best known compound of this type, a-chloroethyl chloroformate (ACE-C1), is a mild reagent for the selective N-dealkylation of tertiary amines with commercial value. Both ACE-C1 and its congener from chloral are protecting groups for alcohols The derived carbonates are efficient precursors to fluoroformates including the important t-butyl fluoroformate. Applications in which fluoroformates are superior to chloroformates are outlined The elimination of HC1 from the carbamates/carbonates easily formed from 2 is described. (From the surprising carbonate elimination mechanism, a simple synthesis of aldehyde enolates under preparatively useful conditions has been discovered.) The product vinylic carbamates and carbonates are monomer precursors to vinyl polymers with urethan and carbonate branches. 2,2-Dihalovinyl chloroformates also have been made and converted to carbamate and carbonate monomers. Finally, 3- and 4-carbon synthons available by extensions of the above chemistry are introduced. © 1988 IUPAC