Issue 29, 2017

Borata-Wittig olefination reactions of ketones, carboxylic esters and amides with bis(pentafluorophenyl)borata-alkene reagents

Abstract

The strongly electrophilic borane derivative amino–CH2CH2CH2–B(C6F5)26 was α-CH deprotonated with LiTMP to give the borata-alkene {[amino–(CH2)2–CH[double bond, length as m-dash]B(C6F5)2][Li+]}29 which underwent facile [2 + 2] cycloaddition reactions with benzophenone or fluorenone to yield the respective 1,2-oxaboretanides 11a,b. Compounds 9 and 11 were characterized by the X-ray diffraction. Thermolysis or hydrolysis of compounds 11a,b gave the corresponding borata-Wittig olefination products 12a,b. A variety of R–CH2–CH2–B(C6F5)2 boranes (conveniently generated by hydroboration of terminal alkenes R–CH[double bond, length as m-dash]CH2 with Piers’ borane [HB(C6F5)2]) were analogously deprotonated to give the respective borata-alkenes 16a–e (R: Ph–CH2–, nC4H9, tBu, Cy, PhCH2CH2–). They underwent “non-classical” borata-Wittig olefination reactions with ethylformate to give the respective enolether carbonylation products, or their C1-elongated aldehydes (after hydrolysis). The borata-alkene [Ph–(CH2)2–CH[double bond, length as m-dash]B(C6F5)2] [Li+HTMP] (16a) gave the respective “non-classical” borata-Wittig olefination products, the enolethers 25a,b and 27, respectively, upon treatment with methyl- or ethyl acetate or γ-butyrolactone.

Graphical abstract: Borata-Wittig olefination reactions of ketones, carboxylic esters and amides with bis(pentafluorophenyl)borata-alkene reagents

Supplementary files

Article information

Article type
Paper
Submitted
23 May 2017
Accepted
30 Jun 2017
First published
30 Jun 2017

Org. Biomol. Chem., 2017,15, 6223-6232

Borata-Wittig olefination reactions of ketones, carboxylic esters and amides with bis(pentafluorophenyl)borata-alkene reagents

T. Wang, S. Kohrt, C. G. Daniliuc, G. Kehr and G. Erker, Org. Biomol. Chem., 2017, 15, 6223 DOI: 10.1039/C7OB01591G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements