PROCESS FOR PREPARING E-5-BROMOPENETENE-2 Russian patent published in 1996 - IPC

FIELD: synthesis of organic compounds. SUBSTANCE: two-stage treatment of the starting cyclopropyl ethanol first with phosphorus tribromide absolute inert solvent in the presence of anhydrous lithium salt and organic base, e.g. pyridine at temperature of from minus 10 to 60 C, the 1- bromo-1-cyclopropylethane thus formed is treated with anhydrous zinc bromide in absolute inert solvent, e.g. diethyl ether or tetrahydrofuran at temperrature of minus 10 to 50 C to give 5-bromopenetene-2E (trans) configuration of 96 % regio- and stereochemical purity with yield of at least 80%. EFFECT: more efficient preparation process. 5 cl