81570-20-9Relevant academic research and scientific papers
An asymmetric synthesis of a 1α,25-dihydroxyvitamin D3 A-ring synthon
Chen,Crich
, p. 1945 - 1948 (1992)
An efficient asymmetric synthesis of the A-ring of 1α,25-dihydroxyvitamin D3 from α-bromoacrolein is described. The key steps of the synthesis are the Evans type syn-selective asymmetric aldol reaction of bromoacrolein with the boron enolate of
Radical cyclization in heterocycle synthesis. 12. Sulfanyl radical addition-addition-cyclization (SRAAC) of unbranched diynes and its application to the synthesis of A-ring fragment of 1 α,25-dihydroxyvitamin d3
Miyata,Nakajima,Naito
, p. 213 - 224 (2007/10/03)
Sulfanyl radical addition-addition-cyclization (SRAAC) of unbranched diynes proceeded smoothly to give cyclized exo-olefins, while the sulfanyl radical addition-cyclization-addition (SRACA) of diynes having a quaternary carbon gave cyclized endo-olefins. This method was successfully applied to the synthesis of A-ring fragment of 1 α,25-dihydroxyvitamin D3.
An efficient enantioselective synthesis of 1α,25-dihydroxyvitamin D3 A-ring synthon
Koiwa, Masakazu,Hareau, Georges P.J.,Sato, Fumie
, p. 2389 - 2390 (2007/10/03)
The asymmetric synthesis of the A-ring of 1α,25-dihydroxyvitamin D3, (Z)-2, from 5-tert-butyldimethylsiloxy-2-cyclohexenone [(S)-1], is described where an intramolecular lactonization using cat. scandium triflate is the key reaction. (C) 2000 Elsevier Science Ltd.
Concise Enantiocontrolled Synthesis of the A-Ring Precursor of Calcitriol from the Chiral Cyclohexadienone Synthon
Kamikubo, Takashi,Ogasawara, Kunio
, p. 1951 - 1952 (2007/10/02)
A new and concise enantiocontrolled route to the A-ring precursor of calcitriol is developed by utilizing the chiral cyclohexane-2,5-dienone synthon.
The Cyclization Route to the Calcitriol A-ring: A Formal Synthesis of (+)-1α,25-Dihydroxyvitamin D3
Chen, Chen,Crich, David
, p. 7943 - 7954 (2007/10/02)
An efficient asymmetric synthesis of the A-ring of 1α,25-dihydroxyvitamin D3 from α-bromoacrolein is described.The key steps of the synthesis are the Evans type syn-selective asymmetric aldol reaction of bromoacrolein with the boron enolate of
An Efficient Asymmetric Synthesis of 1α,25-(OH)2 Vitamin D3 A-Ring Synthon
Nagasawa, Kazuo,Ishihara, Hideki,Zako, Yoshiro,Shimizu, Isao
, p. 2523 - 2529 (2007/10/02)
Chiral synthesis of the A-ring synthon 3 of 1α,25-dihydroxyvitamin D3 (1a) based on palladium-catalyzed cyclization of 8-bromo-2,8-nonadienoates is described.Reaction of (E)-4b and (Z)-4d in the presence of Pd(OAc)2, PPh3 and K2CO3 gave (E)-3b and (Z)-3d, respectively.Optically active 4d was prepared from 24 by asymmetric aldol reaction using 31, which was cyclized to 3d.With further reactions, 1α,25-dihydroxyvitamin D3 (1a) was obtained.
A Radical Cyclization Approach to 1α,25-Dihydroxyvitamin D3
Batty, Duncan,Crich, David
, p. 2894 - 2896 (2007/10/02)
An approach to 1α,25-dihydroxyvitamin D3 involving the preparation of the vinyl selenide 8, its cyclization to 9 with tributyltin hydride and the conversion of the latter into the known isomeric dienes 3 and 10 is described.
Stereocontrolled Total Synthesis of 1α,25-Dihydroxycholecalciferol and 1α,25-Dihydroxyergocalciferol
Baggiolini, Enrico G.,Iacobelli, Jerome A.,Hennessy, Bernard M.,Batcho, Andrew D.,Sereno, John F.,Uskokovic, Milan R.
, p. 3098 - 3108 (2007/10/02)
1α,25-dihydroxycholecalciferol (4) and 1α,25-dihydroxyergocalciferol (7), the hormonally active forms of vitamin D3 (1) and vitamin D2 (5), were synthesized by a Horner-Wittig reaction of the phosphine oxide 11 with the ketones 10 and 12, respectively.The synthon 11 was obtained by a sequence that involves the stereospecific opening of epoxide 15, with sodium acetate in acetic acid, followed by oxidative degradation of the isopropenyl side chain and dehydration of the intermediate 22.Photoisomerisation of the resulting 23 gave 24, which was finally converted to 11.The hydroxylated ketone 10 was obtained from the known intermediate 28.The introduction of the 25-hydroxy side chain was achieved by reaction of the lithium derivative of 30 with the tosylate 29 to give 31, which was catalytically hydrogenated to 32 and then converted to 10.The ketone 12 was prepared by a stereocontrolled route that involves as the key step, the dipolar cycloaddition of nitrone 35 with methyl 3,3-dimethylacrylate (36) to give a 1:1 mixture of isoxazolidines 37 and 38.Stereochemical control was achieved by taking advantage of the thermal reversibility of the cycloaddition, which allows the reequilibration of undesired 37.Isoxazolidine 38 was readily transformed to 43 by reduction, followed by elimination of the nitrogen function, and finally oxidation to 12.
