2-(Bicyclopropylidenyl)- and 2-(trans-2′-Cyclopropylcyclopropyl)-4,4,5,5-tetramethyl-1,3-dioxa-2-borolane and Their Palladium-Catalyzed Cross-Coupling Reactions

All articles of this category The bicyclopropylidenylboronate 2 was prepared in 76% yield from lithiated bicyclopropylidene ( 1 ) and 2-isopropyloxy-4,4,5,5-tetramethyl-1,3-dioxa-2-borolane. Birch reduction of 2 furnished 2-( trans -2′-cyclopropylcyclopropyl)-4,4,5,5-tetramethyl-1,3-dioxa-2-borolane ( 3 ) in 79% yield. Under palladium catalysis, the latter was successfully coupled with a variety of aryl and alkenyl halides to give the corresponding (2′-cyclopropylcyclopropyl)-substituted arene 6 (52-75% yield) and alkene derivatives 11 a, b (48-59%), respectively. Twofold and even threefold couplings of 2 with 1,2-dibromo- and 1,3,5-tribromobenzene were also successful. trans -3-(2′-Cyclopropylcyclopropyl)acrylic acid 12 could easily be obtained from 11 a in 74% yield. palladium catalysis - cyclopropane derivatives - cross-coupling - boron - bicyclopropylidene