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Ring-opening of Epoxides Mediated by Frustrated Lewis Pairs.

Authors :
Krachko T
Nicolas E
Ehlers AW
Nieger M
Slootweg JC
Source :
Chemistry (Weinheim an der Bergstrasse, Germany) [Chemistry] 2018 Aug 27; Vol. 24 (48), pp. 12669-12677. Date of Electronic Publication: 2018 Jul 23.
Publication Year :
2018

Abstract

Treatment of the preorganized frustrated Lewis pairs (FLPs) tBu <subscript>2</subscript> PCH <subscript>2</subscript> BPh <subscript>2</subscript> (1) and o-Ph <subscript>2</subscript> P(C <subscript>6</subscript> H <subscript>4</subscript> )BCat (Cat=catechol) (4) with 2-methyloxirane, 2-phenyloxirane and 2-(trifluoromethyl)oxirane resulted in epoxide ring-opening to yield the six- and seven-membered heterocycles 2 a-c and 5 a-c, respectively. These zwitterionic products were characterized spectroscopically, and compounds 2 a, 2 b, 5 a and 5 c were structurally characterized by single-crystal X-ray structure analyses. Based on computational and kinetic studies, the mechanism of these reactions was found to proceed via activation of the epoxide by the Lewis acidic borane moiety followed by nucleophilic attack of the phosphine of a second FLP molecule. The resulting chain-like intermediates afford the final cyclic products by ring-closure and concurrent release of the second equivalent of FLP that behaves as catalyst in this reaction.<br /> (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Details

Language :
English
ISSN :
1521-3765
Volume :
24
Issue :
48
Database :
MEDLINE
Journal :
Chemistry (Weinheim an der Bergstrasse, Germany)
Publication Type :
Academic Journal
Accession number :
29882283
Full Text :
https://doi.org/10.1002/chem.201801909