Construction of NH-Unprotected Spiropyrrolidines and Spiroisoindolines by [4+1] Cyclizations of γ-Azidoboronic Acids with Cyclic N-Sulfonylhydrazones.

Authors :: López L
Cabal MP
Valdés C
Source :: Angewandte Chemie (International ed. in English) [Angew Chem Int Ed Engl] 2022 Jan 10; Vol. 61 (2), pp. e202113370. Date of Electronic Publication: 2021 Nov 25.
Publication Year :: 2022
Abstract: The reactions of N-sulfonylhydrazones derived from cyclic ketones with γ-azidopropylboronic acid and 2-(azidomethyl)phenylboronic acid give rise to spirocyclic pyrrolidines and spiroisoindolines, respectively. The reactions proceed without the need of any transition-metal catalyst through a domino process that comprises the formation of a Csp <superscript>3</superscript> -C and a Csp <superscript>3</superscript> -N bond of the former hydrazonic carbon. The scope of the reaction has been explored by the preparation of over 50 examples of NH-unprotected spirocyclic derivatives. Importantly, this methodology could be applied for the preparation of alkaloid steroids from steroid N-tosylhydrazones.<br /> (© 2021 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

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