Lewis acidic boranes have been shown to be effective metal-free catalysts for highly selective reactions of donor-acceptor diazo compounds to a range of substrates. The reactions of α-aryl α-diazoesters with nitrogen heterocycles indole or pyrrole selectively generate C3 and C2 C–H insertion products, respectively, in good to excellent yields even when using unprotected indoles. Alternatively, benzofuran, indene, and alkene substrates give exclusively cyclopropanated products with α-aryl α-diazoesters, whereas the reactions with furans lead to ring-opening. Comprehensive theoretical calculations have been used to explain the differing reactivities and high selectivities of these reactions. Overall, this work demonstrates the selective metal-free catalytic reactions of α-aryl α-diazoesters with (hetero)cycles and alkenes. This simple, mild reaction protocol represents an alternative to the commonly used precious metal systems and may provide future applications in the generation of biologically active compounds.

Item Type:	Refereed Article
Keywords:	DFT analysis, cyclopropanation, C–H activation, borane catalysis, ring- opening reactions
Research Division:	Chemical Sciences
Research Group:	Organic chemistry
Research Field:	Physical organic chemistry
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the chemical sciences
UTAS Author:	Babaahmadi, R (Mr Rasool Babaahmadi)
UTAS Author:	Yates, BF (Professor Brian Yates)
UTAS Author:	Ariafard, A (Associate Professor Alireza Ariafard)
ID Code:	142015
Year Published:	2020
Funding Support:	Australian Research Council (DP180100904)
Web of Science® Times Cited:	19
Deposited By:	Chemistry
Deposited On:	2020-12-08
Last Modified:	2021-07-05
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