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Rearrangements of Furan‐, Thiophene‐ and N ‐Boc‐Pyrrole‐Derived Donor‐Acceptor Cyclopropanes: Scope and Limitations
Author(s) -
Kaschel Johannes,
Schneider Tobias F.,
Schirmer Patrick,
Maaß Christian,
Stalke Dietmar,
Werz Daniel B.
Publication year - 2013
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201300390
Subject(s) - chemistry , furan , thiophene , annulation , pyrrole , ring (chemistry) , cyclopropane , sulfur , medicinal chemistry , acceptor , nitrogen , stereochemistry , organic chemistry , catalysis , physics , condensed matter physics
Rearrangements of furan‐, thiophene‐ and N ‐Boc‐pyrrole‐derived donor–acceptor cyclopropanes initiated by Brønsted acids were investigated. Throughout the study, ketones or aldehydes were utilized as accepting moieties and oxygen, sulfur and Boc‐protected nitrogen were used as the donor atoms. Whether a ring‐enlargement and thus an annelation of a five‐membered ring, or a ring‐opening of the three‐membered ring followed by rearomatization to the parent heterocycles takes place strongly depends on the substitution pattern of the cyclopropane. Commonly, more substituted substrates led to annelation whereas less substituted substrates tend to undergo rearomatization. In general, good yields were obtained for starting materials with oxygen and nitrogen donors, whereas the reactions with sulfur as donor gave only poor yields.