TY  - JOUR
A1  - Kaese, Thomas
A1  - Trageser, Timo
A1  - Budy, Hendrik
A1  - Bolte, Michael
A1  - Lerner, Hans-Wolfram
A1  - Wagner, Matthias
T1  - A redox-active diborane platform performs C(sp3)–H activation and nucleophilic substitution reactions
T2  - Chemical science
N2  - Organoboranes are among the most versatile and widely used reagents in synthetic chemistry. A significant further expansion of their application spectrum would be achievable if boron-containing reactive intermediates capable of inserting into C–H bonds or performing nucleophilic substitution reactions were readily available. However, current progress in the field is still hampered by a lack of universal design concepts and mechanistic understanding. Herein we report that the doubly arylene-bridged diborane(6) 1H2 and its B[double bond, length as m-dash]B-bonded formal deprotonation product Li2[1] can activate the particularly inert C(sp3)–H bonds of added H3CLi and H3CCl, respectively. The first case involves the attack of [H3C]− on a Lewis-acidic boron center, whereas the second case follows a polarity-inverted pathway with nucleophilic attack of the B[double bond, length as m-dash]B double bond on H3CCl. Mechanistic details were elucidated by means of deuterium-labeled reagents, a radical clock, α,ω-dihaloalkane substrates, the experimental identification of key intermediates, and quantum-chemical calculations. It turned out that both systems, H3CLi/1H2 and H3CCl/Li2[1], ultimately funnel into the same reaction pathway, which likely proceeds past a borylene-type intermediate and requires the cooperative interaction of both boron atoms.
Y1  - 2018
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/46509
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-465090
SN  - 2041-6539
SN  - 2041-6520
N1  - This article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
VL  - 9
IS  - 15
SP  - 3881
EP  - 3891
PB  - RSC
CY  - Cambridge
ER  -