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Unsaturated C 3 B 2 Rings with Neighboring Boron Atoms: Derivatives of 4‐Methylene‐1,2‐dibora‐cyclopentane, Dilithium 2,3‐diboratafulvene, and 1,2‐Dibora‐3‐yclopentene
Author(s) -
Herberich Gerhard E.,
Ganter Christian,
Wesemann Lars,
Boese Roland
Publication year - 1990
Publication title -
angewandte chemie international edition in english
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 0570-0833
DOI - 10.1002/anie.199009121
Subject(s) - cyclopentane , chemistry , trimethylenemethane , protonation , cyclopentadiene , methylene , dilithium , medicinal chemistry , ring (chemistry) , metalation , methylene bridge , cyclohexane , boron , stereochemistry , deprotonation , organic chemistry , cycloaddition , catalysis , ion
Among the unsaturated BC heterocycles , those with BB groups in the ring are especially difficult to synthesize. By borylation of the trimethylenemethane dianion and reaction of the product with HCl it has now been possible to synthesize the first 1,2‐C 3 B 2 compounds 1 – 3 . Compound 1 , R = i Pr, has an unusual twist conformation in the Crystal. Metalation of 1 with bulky, strong bases affords 3,4‐diboratafulvenes 2 ; their protonation with cyclopentadiene yields 4‐methyl‐1,2‐dibora‐3‐cyclopentane derivatives 3 , R = Et, i Pr.