Crystallization of 1alpha-Hydroxy-2-Methylene-18,19-Dinor-Homopregnacalciferol
a technology of homopregnacalciferol and methyl methyl methyl, which is applied in the field of crystallization of 1alpha-hydroxy-2-methylene-18, 19-dinor-homopregnacalciferol, can solve the problems of chromatographic purification, inability to provide compounds sufficiently pure for use as drugs, and inability to ensure the purity of the final product, etc., to achieve the effect of easy removal
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example 1
Crystallization from Ethyl Acetate / Hexane
[0032]1.25 g of prepurified (see U.S. Pat. No. 7,238,681) crude 1α-hydroxy-2-methylene-18,19-dinor-homopregnacalciferol was dissolved in ethyl acetate (3 ml) at room temperature and hexane (300 ml) was poured into the vigorously shaken solution. The mixture was kept in a refrigerator (at 4° C.) overnight and the resulted crystals were filtered off, washed with one portion (30 ml) of cooled (4° C.) hexane and dried under reduced pressure for 3 h giving 1.10 g of a pure product.
[0033]In order to obtain crystals acceptable for the X-ray experiment, 1α-Hydroxy-2-methylene-18,19-dinor-homopregnacalciferol (12 mg) was placed in an inner tube of a vessel and dissolved in 300 μl of benzene. To an outer tube of the vessel hexane (2 ml) was poured so that a benzene to hexane ratio of about 13:87, by volume, is obtained, and the whole system was carefully purged with argon, and then maintained as a closed system. The vessel was kept tightly closed for 4...
example 2
Synthesis of 051810
[0037]The preparation of 051810 having the basic structure I can be accomplished by a common general method, i.e. the condensation of a bicyclic Windaus-Grundmann type ketone II with the allylic phosphine oxide III to the corresponding 2-methylene-19-nor-vitamin D analog IV followed by deprotection at C-1 and C-3 in the latter compound IV to obtain compound I, i.e. 051810.
[0038]In phosphine oxide III, Y1 and Y2 are preferably hydroxy-protecting groups such as silyl protecting groups. The t-butyldimethylsilyl (TMDMS) group is an example of a particularly useful hydroxy-protecting group. The process described above represents an application of the convergent synthesis concept, which has been applied effectively to the preparation of numerous vitamin D compounds (see Lythgoe et al., J. Chem. Soc. Perkin Trans. I, 590 (1978); Lythgoe, Chem. Soc. Rev. 9, 449 (1983); Toh et al., J. Org. Chem. 48, 1414 (1983); Baggiolini et al., J. Org. Chem. 51, 3098 (1986); Sardina et ...
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