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Synlett 2001; 2001(4): 0489-0492
DOI: 10.1055/s-2001-12320
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2-(Bicyclopropylidenyl)- and 2-(trans-2′-Cyclopropylcyclopropyl)-4,4,5,5-tetramethyl-1,3-dioxa-2-borolane and Their Palladium-Catalyzed Cross-Coupling Reactions

Sandra Löhr* , Armin de Meijere
  • *Institut für Organische Chemie, Georg-August-Universität Göttingen, Tammannstrasse 2, 37077 Göttingen, Germany; Fax + 49(551)39-9475; E-mail: Armin.deMeijere@chemie.uni-goettingen.de
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Publication History

Publication Date:
31 December 2001 (online)

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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