Synthesis of deuterium-labeled androst-5-ene-17 beta,19-diol and its 4-eneisomer as internal standards for the determination of the 19-oxygenation of aromatase inhibitors using GC-MS

[3 beta,7,7,17 alpha-H-2(4)]Androst-5-ene-17 beta,19-diol (6) and [3,3,7,7, -H-2(4)]androst-4-ene-17 beta,19-diol (15-d(4)) were synthesized as interna l standards for gas chromatographic-mass spectrometric analysis of the 19-h ydroxylation of androst-5-en-17-one (1) and its 4-ene isomer 2, inhibitors of estrogen biosynthesis, using human placental aromatase. Treatment of [7, 7-H-2(2)]3 beta-tosylate 3 with Zn-NaI-D2O, followed by reduction with NaBD 4, gave compound 6 (d(4), 79.8 atom%). Compound 15-d4 was synthesized via 3 beta,17 beta-dihydroxy-5-en-7-one 10 as a key intermediate. Deoxygenation of the 5-en-7-one 10 and [7,7-2H2]17 beta-hydroxy-4-en-3-one 13-d(2), produ ced from compound 10 in two steps, with AlCl2D2 was used for the deuterium labeling reaction, producing compound 15-d(4) (d(4), 93.5 atom%). The 19-ox ygenation products of aromatase inhibitors 1 and 2 could be analyzed, after NaBH4, reduction, as the corresponding 17 beta,19-diol bis-trimethylsilyl ethers using the internal standards and 15-d(4).