Issue 6, 2020

Borane-induced ring closure reaction of oligomethylene-linked bis-allenes

Abstract

The trimethylene-linked bis-allene 3a reacts with Piers' borane [HB(C6F5)2] by a hydroboration/allylboration sequence to generate the cyclization product 5a. Its pyridine adduct was isolated and characterized by X-ray diffraction. Compound 5a undergoes a typical frustrated Lewis pair 1,2-P/B alkene addition reaction with PPh3 to give the heterobicyclic bridged olefinic zwitterionic product 9a. The tetramethylene-linked bis-allene 3b and its phenylene annulated analogue 3c react with HB(C6F5)2 to give the analogous seven-membered ring products 5b,c under mild conditions. The cyclization product 5a undergoes a series of sequential allylboration reactions with two equivalents of allene followed by ring-closure to give the four-component coupling product 12a. It undergoes FLP addition to an exo-methylene group upon treatment with PPh3. Compound 12a is oxidatively converted to the boron-free alcohol.

Graphical abstract: Borane-induced ring closure reaction of oligomethylene-linked bis-allenes

Supplementary files

Article information

Article type
Edge Article
Submitted
03 Aug 2019
Accepted
17 Dec 2019
First published
18 Dec 2019
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2020,11, 1542-1548

Borane-induced ring closure reaction of oligomethylene-linked bis-allenes

X. Tao, K. Škoch, C. G. Daniliuc, G. Kehr and G. Erker, Chem. Sci., 2020, 11, 1542 DOI: 10.1039/C9SC03870A

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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