Synthesis of Deuterium-Labeled Androst-5-ene-17.BETA.,19-diol and Its 4-Ene Isomer as Internal Standards for the Determination of the 19-Oxygenation of Aromatase Inhibitors Using GC-MS.

Abstract

[3β, 7, 7, 17α-2H4]Androst-5-ene-17β, 19-diol (6) and [3, 3, 7, 7, -2H4]androst-4-ene-17β, 19-diol (15-d4) were synthesized as internal standards for gas chromatographic-mass spectrometric analysis of the 19-hydroxylation of androst-5-en-17-one (1) and its 4-ene isomer 2, inhibitors of estrogen biosynthesis, using human placental aromatase. Treatment of [7, 7-2H2]3β-tosylate 3 with Zn-NaI-D2O, followed by reduction with NaBD4, gave compound 6 (d4, 79.8 atom%). Compound 15-d4 was synthesized via 3β, 17β-dihydroxy-5-en-7-one 10 as a key intermediate. Deoxygenation of the 5-en-7-one 10 and [7, 7-2H2]17β-hydroxy-4-en-3-one 13-d2, produced from compound 10 in two steps, with AlCl2D2 was used for the deuterium labeling reaction, producing compound 15-d4 (d4, 93.5 atom%). The 19-oxygenation products of aromatase inhibitors 1 and 2 could be analyzed, after NaBH4 reduction, as the corresponding 17β, 19-diol bis-trimethylsilyl ethers using the internal standards 6 and 15-d4.