Bromotrimethylsilane → HCID 54212929, compound

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Reaction Steps

A solution of 3.1 g of acid 7 and 3 ml of N,O-bis-trimethylsilylacetamide in 200 ml of dry dichloromethane is stirred at room temperature for one hour. 3.5 ml of trimethylbromosilane are added, and the mixture is stirred at room temperature for 30 hours. The volatile portions are evaporated off, the residue is taken up in 50 ml of dichloromethane, and 250 ml of water are added at 0°-2°. The aqueous phase is separated off and concentrated to 10 ml under a high vacuum. Chromatography on 20 ml of Dowex® 50 W×8 using water as eluant, and lyophilisation of the eluate yield 1.04 g of 8 H2O); 13C-NMR (75 MHz, D2O): 172.8 (CO2H); 140.3 (C(4)); 122.2 (C(3)); 56.4 (C(2)); 33.3 (d, J=17, C(5)); 27.3 (d, J=134, C(7 )); 22.6 (d, J=4, C(6)). In order to analyse the purity of the enantiomer, a sample is derivatised to the amide trimethyl ester with (R)-(+)-methoxytrifluoromethylphenylacetic acid chloride followed by diazomethane. 1H-NMR analysis (300 MHz) by integration of the OCH: signals gives ≥95% (2R)-isomer (3.54 ppm) and ≤5% (2S)-isomer (3.37 ppm).

Provenance & Evidence