A facile method for steroid labeling by heavy isotopes of hydrogen

The labeling of brassinosteroids by tritium

“…13 On the other hand, we have shown that it is possible to perform catalytic reductive dehalogenation of chlorocarbonate 3 obtained by the reaction of the corresponding a-hydroxy ketone with triphosgene in a nearly quantitative yield. The subsequent conversion of such hydroxyketon 9 into an appropriate chlorocarbonate 10 failed under the reaction conditions 12,13 used for an otherwise very efficient synthesis of chlorocarbonate 3, in other cases always affording a quantitative yield of an appropriate chlorocarbonate. Chlorocarbonate 3 was chosen as the starting molecule for such a synthetic transformation.…”

“…[12][13][14] An endiol form of such an a-hydroxy ketone is a suitable substrate for synthetic transformations leading to an appropriate bis-substituted endiol 11 or chlorocarbonate. [12][13][14] An endiol form of such an a-hydroxy ketone is a suitable substrate for synthetic transformations leading to an appropriate bis-substituted endiol 11 or chlorocarbonate.…”

“…[12][13][14] An endiol form of such an a-hydroxy ketone is a suitable substrate for synthetic transformations leading to an appropriate bis-substituted endiol 11 or chlorocarbonate. 13 On the other hand, we have shown that it is possible to perform catalytic reductive dehalogenation of chlorocarbonate 3 obtained by the reaction of the corresponding a-hydroxy ketone with triphosgene in a nearly quantitative yield. 12,13 Moreover, the other attempted methods of the creation of a reducible double bond on the steroid skeleton from the a-hydroxy ketone group failed.…”

“…12,13 Moreover, the other attempted methods of the creation of a reducible double bond on the steroid skeleton from the a-hydroxy ketone group failed. 12,13 The vicinal diol 8, obtained aer selective deprotection of 3 by FeCl 3 in a yield of 87% (Experimental section, 4.1. The reduction of 3 by gaseous carrier-free tritium catalyzed by PdO/ CaCO 3 in the presence of Et 3 N followed by the removal of protecting groups provided 24-[3b- 3 To obtain a product with an even higher specic activity, we attempted to synthesize derivative 10, possessing two chlorocarbonate groups in the BR skeleton.…”

“…[2][3][4][5] Recently, the pioneer work of Strnad et al has revealed that some natural BRs induce cell-growthinhibitory responses in several human cancer cell lines at micromolar concentration without affecting normal non-tumor cell growth (BJ broblasts). [11][12][13] A detailed study of regio-specically tritium-labeled brassinosteroids with a very high specic activity (SA) is reported in this paper. 1).…”