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Stereoconvergent Generation of a Contrasteric syn ‐Bicyclopropylidene (= syn ‐Cyclopropylidenecyclopropane) by Stille ‐Like Coupling
Author(s) -
Güney Murat,
Eşsiz Selçuk,
Daştan Arif,
Balci Metin,
De Lucchi Ottorino,
Şahin Ertan,
Fabris Fabrizio
Publication year - 2013
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.201200291
Subject(s) - chemistry , transmetalation , stille reaction , tin , carbenoid , cyclopropane , stereochemistry , diastereomer , lithium (medication) , single crystal , copper , crystallography , organic chemistry , rhodium , catalysis , medicine , ring (chemistry) , endocrinology
Stereoisomerically pure endo‐ and exo‐ 7‐halo‐7‐(trimethylstannyl)benzonorcar‐3‐enes (= endo ‐ and exo ‐(1‐halo‐1a,2,7,7a‐tetrahydro‐1 H ‐cyclopropa[ b ]naphthalen‐1‐yl)trimethylstannane) 4 and 6 were selectively obtained by lithiumtin or magnesiumtin transmetalation in good yields ( Scheme 2 and 3 ). The reaction of these compounds with copper(I) thiophene‐2‐carboxylate (CuTC) produced in both cases the corresponding C S ‐symmetric bicyclopropylidene (=cyclopropylidenecyclopropane) syn ‐ 1 , a single diastereoisomer ( Schemes 5 and 6 ). The structure of syn ‐ 1 was undoubtedly elucidated by X‐ray single crystal diffraction. The coupling mechanism of the carbenoid cyclopropane is discussed ( Scheme 7 ).