147125-20-0Relevant academic research and scientific papers
The synthesis of [26,27-11C]dihydroxyvitamin D3, a tracer for positron emission tomography (PET)
Bonasera, Thomas A.,Grue-Sorensen, Gunnar,Ortu, Giuseppina,Binderup, Ernst,Bergstroem, Mats,Bjoerkling, Fredrik,Langstroem, Bengt
, p. 3123 - 3128 (2007/10/03)
1α,25-Dihydroxyvitamin D3, an endogenous ligand with the highest affinity for the vitamin D receptor (VDR), was labeled with 11C for use in biological experiments. The radionuclide was incorporated via the reaction of [11C]methyllithium on a methyl ketone precursor in tetrahydrofuran at -10°C. Deprotection of the labeled intermediate yielded 2.5-3 GBq [26,27-11C]1α,25-dihydroxyvitamin D3 [11C-1,25(OH)2 D3] with specific radioactivity averaging 100 GBq/μmol at the end of synthesis and HPLC purification. The entire process took 48 min from the end of radionuclide production. In vitro binding experiments in rachitic chick purified VDR demonstrated the high affinity binding of this novel tracer. Thus; 11C-1,25(OH)2 D3 is available for in vivo distribution studies and may be suitable for the positron emission tomography (PET) determination of VDR levels and occupancy in animals and humans.
Nickel-Mediated Conjugate Addition. Elaboration of Calcitriol from Ergocalciferol
Manchand, Percy S.,Yinnikouros, George P.,Belica, Peter S.,Madan, Pradeep
, p. 6574 - 6581 (2007/10/03)
A convenient method for introduction the side chain of the hormone calcitriol (3) was achieved by coupling the nickel(0) complex derived from ethyl acrylate with the C-22 iodides 15, 16, 27, and 30 to give the corresponding esters 18, 21, 28, and 23 in yields of 73-82percent.Iodide 15 was also coupled with the Ni(0) complex derived from methyl vinyl ketone.The C-22 iodides 15 and 27 were obtained from ergocalciferol (6) and the 1(S),3(R)-bis-(5E,7E)-ergocalciferol derivative 24, respectively, by selective ozonolysis of their SO2 adducts, followed by in situ reduction of the ozonides with NaBH4 and iodination of the derived alcohols 14 and 26 with I2/PPh3/imidazole.The triene iodide 16 was prepared by extrusion of SO2 from 15, while 30 was obtained from the corresponding alcohol 29.Extrusion of SO2 from 21 and 28 gave the 5(E),7(E)-trienes 18 and 23, respectively.The latter was also made from the former by C-1 hydroxylation with selenium dioxide followed by silylation with tert-butyldimethylsilyl chloride and chromatographic separation.Completion of the synthesis of 3 was accomplished by treating 23 with methylmagnesium bromide to give 31, followed by desilylation with n-Bu4NF and triplet-sensitized photoisomerization.Alternatively, 31 was photoisomerized to 33, desilylation of which gave 3.Alcohol 33 was also prepared by the reaction of the 5Z,7E-triene ester 34, which was obtained by the photoisomerization of 23, with methylmagnesium bromide.
