Synthesis of Z‐ and E‐[2,3‐2H2] and [2,3‐3H2]‐1,1‐dichloro‐2,3‐ diphenylcyclopropane (2H‐ and 3H‐analog II and its trans isomer)

Abstract

Abstract2H and 3H labeled Z‐ and E‐1,1‐dichloro‐2,3‐diphenylcyclopropane (1 and 2) were synthesized starting from NaB2H4 and NaB3H4 reduction of benzil. The resulting glycols were transformed to the 1,2‐labeled Z‐ and E‐stilbenes by thermolysis of their cyclic thionocarbonates in trimethylphosphite. The stilbenes were reacted with phase transfer‐generated dichlorocarbene to form the title compounds. The dideuterio isomers were separated by fractional crystallization in yields of 60 and 48%. Each was greater than 99 % geometrically and 98 % isotopically pure. The ditritio isomers were separated by C‐18 JPLC. The radiochemical yields, on a molar basis using benzil as the limiting reagent, were 42 % and 23 %, each with specific activity of 88.5 mCi/mmol and radiochemical purity of > 95%.