A facile synthesis of 3,3,4,4,3 ',3 ',4 ',4 '-homocystine-d(8)

We describe the synthesis of 3,3,4,4,3',3',4',4'-homocystine-d(8) 2 in four steps. Compound 2 has been utilized as an internal standard for the LC-MS quantification of L-homocysteine 1, a marker for cardiac disease. 1,1,2,2-T etradeutero-2-bromoethyl triphenylmethyl sulfide 4 was treated with the dia nion of N-(tert-butoxycarbonyl) glycine tert-butyl ester 5 giving the homoc ysteine derivative 6. Oxidation of 6 with iodine in methanol gave the homoc ystine precursor 7. Subsequent deprotection provided 2 in high chemical pur ity (99%) as measured by analytical HPLC and isotopic purity of >99% as det ermined by mass spectrometry.