(+)-9-(1S,2S-Pseudoephedrinyl)-(10R)-(trimethylsilyl)-9-borabicyclo[3.3.2]decane

Abstract

[848701-34-8] C22H38BNOSi (MW 371.44) InChI = 1S/C22H38BNOSi/c1-17(24-2)21(18-11-7-6-8-12-18)25-23-20-15-9-13-19(14-10-16-20)22(23)26(3,4)5/h6-8,11-12,17,19-22,24H,9-10,13-16H2,1-5H3/t17-,19-,20+,21+,22?/m0/s1 InChIKey = ZOZYQBFBLCMBTA-FQXALJIWSA-N (chiral pseudoephedrine borinic acid derivative for the preparation of reagents for the asymmetric hydroboration, allyl-, allenyl-, crotyl-, propargyl-, and alkynylation of aldehydes and aldimines through Grignard or organolithium procedures) Physical Data: mp 130–134 °C, (c = 4.5, CDCl3). Solubility: sol CHCl3, CH2Cl2, THF. Preparation: both enantiomers are available in pure form from the transesterification of racemic B-MeO-10-TMS-9-BBD (TMSCHN2 plus B-MeO-9-BBN) with pseudoephedrine in MeCN; the sequential protocol utilizes both enantiomers of pseudoephedrine to provide both enantiomers (ca. 66% total yield) of the borinate complexes in a single procedure. Analysis of Reagent Purity: in solution, both the open and closed forms of the complex can be observed through 13C NMR by analyzing the TMS signal of the complex in CDCl3 (δ 1.7 (open) and δ 0.7 (closed)). Even very minor amounts of the undesired diastereomer (δ 1.1) can be observed if present.2 Recrystallization (MeCN/CH2Cl2 ∼8:1 (0.5 M)) after complete dissolution at reflux (20–40 h) gives the pure crystalline enantiomer. Form Supplied in: colorless crystalline solid (Scheme 1); both enantiomers are commercially available. Scheme 1. Handling, Storage, and Precautions: crystalline solid that can be handled in the open atmosphere; best stored under dry nitrogen to preserve product purity.