51467-57-3Relevant articles and documents
Motional Anisotropy-Induced Unequal Deuterium NMR Spin-Lattice Relaxation of 3α-Deuteriocholesterol and 3β-Deuterioepicholesterol in Solution as a Measure of Sterol Motion about the Molecular Axis
Murari, Martha P.,Murari, Ramaswamy,Baumann, Wolfgang J.
, p. 243 - 245 (1985)
Deuterium spin-lattice relaxation (T1) data for 3α-deuteriocholesterol and 3β-deuterioepicholesterol in solution were obtained at 12.21 MHz as a function of solvent viscosity (η).The correlation times (τc) for both 3-deuteriosterols varied in a linear fashion over the range of viscosities studied.The data showed that although both 3α-deuteriocholesterol and 3β-deuterioepicholesterol undergo rapid reorientations (τc ca. 10-11 s) in solution, the relaxation of the deuterium in α-deuteriocholesterol was approximately 2.5 times faster than in 3β-deuterioepicholesterol.These unequal rates of relaxation are due to the difference in the angles between the C-D bond and the molecular axis for the two sterol isomers.An equation containing an angular-dependent term was derived to analyze the T1 data further.The effective correlation times (τeff), thus calculated, converged for identical viscosities.In the case of 3α-deuteriocholesterol, it was determined that rotation about the molecular axis comprised up to 60percent of the motions relaxing the deuteron.The results show that for molecules having an inherent anisotropy and undergoing isotropic motions, it is possible to separate the portion of motion due to rotation about the molecular axis from other motions, it is possible to separate the portion of motion due to rotation about the molecular axis from other motions which contribute to the relaxation processes at a specific center.
Photo-induced Transformations. Part 51. Photo- and Thermally-induced Rearrandements of Hypoiodites of Steroidal Homoallyl Alcohols. The Formation of Some Oxygen Heterocycles via Photo- and Thermally-induced Rearrangements of 3-Hydroxy-Δ5-steroid Hypoiodites in the Presence of ...
Suginome, Hiroshi,Furusaki, Akio,Kato, Kimitoshi,Maeda, Norio,Yonebayashi, Fumihiko
, p. 236 - 250 (2007/10/02)
Hypoiodites of cholesterol and epicholesterol in benzene containing mercury (II) oxide and iodine underwent photo-induced rearrangement to give 3α,5-epoxy-6β- and -6α-iodo-A-homo-4-oxa-5α-cholestanes (3) and (4), together with 3-formyloxy-2-iodo-A-nor-2,3-secocholest-5-ene (2).Stereochemistry of the epoxide (3) was established by an X-ray crystallographic analysis.When the reaction of cholesterol hypoiodite was induced thermally at 55-60 deg C, only the 6β-isomer, accompanied by cholest-5-en-3α-yl A-homo-4-oxacholest-5-en-3α-yl ether (20) and A-homo-4-oxacholest-5-en-3α-ol (21), is formed.Catalytic hydrogenolysis of iodo-epoxide (3) or (4) gave 3α,5-epoxy-A-homo-4-oxa-5β-cholestane (16) which was transformed into 2-acetyl-5-acetoxymethyl-4-oxa-5β-cholest-2-ene (29) upon treatment with boron trifluoride-ether-acetic anhydride in benzene.In contrast, the newly synthesized hypoiodite of 3α,4,4-trimethylcholest-5-en-3β-ol, in benzene containing mercury (II) oxide and iodine, gave 2-acetyl-3-oxacholest-5-enes (26) and (27) together with 3α,5α-epoxy-A-homo-4-oxasteroids (24) and (25) on irradiation or thermolysis.The formation of the products (26) and (27) indicates the intervention of a common oxyl radical (E) in the rearrangements of 3-hydroxy-Δ5-steroid hypoiodites to products (3), (4), (24), (25), (26), and (27).The pathways of the rearrangements and the stereoselectivity of the reactions are discussed.
