合成路线1

3-Mercapto-3-methylbutyric acid (I) was protected as the tetrahydropyranyl derivative (III) using dihydropyran (II) and HCl. Subsequent treatment of (III) with triphosgene and triethylamine generated the acid anhydride (IV). Condensation of yohimbine (V) with anhydride (IV) in the presence of dimethylaminopyridine provided ester (VI). Further acetylation of (VI) with acetyl chloride in acetic acid gave rise to the N,S-diacetyl compound (VII), which was selectively deacetylated with mercuric trifluoroacetate, yielding thiol (VIII). Finally, reaction of (VIII) with NaNO2 and HCl furnished the corresponding S-nitrosyl derivative.