[99966-26-4]  · C9H17BO  · 10-Methyl-10-bora-9-oxabicyclo[3.3.2]decane  · (MW 152.07)

(air-stable methylating agent via Suzuki-Miyaura coupling1)

Physical Data: bp 50 °C/3 mmHg.1,2

Solubility: sol organic solvents; insol water.2

Analysis of Reagent Purity: can be isolated in pure form and analyzed efficiently by GC or standard spectroscopic techniques (e.g. 11B NMR (CDCl3) d 54.7 ppm).2

Preparative Methods: a one-pot sequence (57%) from B-MeO-9-BBN by reaction with MeLi in Et2O at -78 °C, followed by Trimethylamine N-Oxide (TMANO) (1 equiv) in CH2Cl2 at 0 °C.1 Alternatively, the intermediate B-Me-9-BBN can be isolated and oxidized with TMANO in CHCl3 at 0 °C to afford the reagent (81%).2

Handling, Storage, and Precautions: indefinitely stable at 25 °C when stored under a nitrogen atmosphere; it can also be handled in the open atmosphere for brief periods of time without significant decomposition. Its preparation involves the handling of dangerously pyrophoric or flammable reagents (i.e. B-Me-9-BBN, B-MeO-9-BBN, MeLi). Individuals should thoroughly familiarize themselves with the special handling techniques required for such reagents prior to their use.3

Methylation via Suzuki-Miyaura Coupling.

The highly efficient oxidation of B-alkyl-9-BBN derivatives with TMANO leads to the exclusive formation of 10-alkyl-10-bora-9-oxabicyclo[3.3.2]decanes which are remarkably resistant to further oxidation compared to other borinate esters (eq 1).2 This feature provides alkylboranes which are particularly convenient to handle while still undergoing useful carbon-carbon bond-forming reactions such as Pd-catalyzed cross coupling with alkenyl, alkynyl, and aryl bromides under basic conditions. The process occurs with retention of configuration in the case of the vinyl bromides, and gem-dibromides are efficiently dimethylated (eq 2).1

Related Reagents.


1. (a) Soderquist, J. A.; Santiago, B. TL 1990, 31, 5541. See also: (b) Soderquist, J. A.; Santiago, B.; Rivera, I. TL 1990, 31, 4981. (c) Rivera, I.; Soderquist, J. A. TL 1991, 32, 2311.
2. Soderquist, J. A.; Najafi, R. M. JOC 1986, 51, 1330.
3. (a) Pelter, A.; Smith, K.; Brown, H. C. Borane Reagents; Academic: London, 1988. (b) Brown, H. C.; Midland, M. M.; Levy, A. B.; Kramer, G. W. Organic Synthesis via Boranes; Wiley: New York, 1975.

John A. Soderquist

University of Puerto Rico, Rio Piedras, Puerto Rico

Copyright 1995-2000 by John Wiley & Sons, Ltd. All rights reserved.