81506-23-2Relevant academic research and scientific papers
Enantioconvergent Preparation of the A-Ring Precursors of Calcitriol from Either (R)- or (S)-Epichlorohydrin
Tazumi, Kazuki,Ogasawara, Kunio
, p. 1903 - 1904 (1994)
Linear and cyclic A-ring precursors of calcitriol have been prepared in both synthetically and enantiomerically convergent ways starting from either (R)- or (S)-epichlorohydrin.
Efficient synthesis of the A-ring phosphine oxide building block useful for 1α,25-dihydroxy vitamin D3 and analogues
Daniewski, Andrzej R.,Garofalo, Lisa M.,Hutchings, Stanley D.,Kabat, Marek M.,Liu, Wen,Okabe, Masami,Radinov, Roumen,Yiannikouros, George P.
, p. 1580 - 1587 (2007/10/03)
The 1α-hydroxy A-ring phosphine oxide 1, a useful building block for vitamin D analogues, was synthesized from (S)-carvone in nine synthetic operations and a single chromatographic purification in 25% overall yield. The synthesis features two novel efficient synthetic transformations: the Criegee rearrangement of α-methoxy hydroperoxyacetate 10 in methanol to obtain directly the desired secondary 3β-alcohol 11 and the highly chemo- and stereoselective isomerization of dieneoxide ester (E)-7 to the 1α-allylic alcohol with an exocyclic double bond (E)-8. Further insight into the selectivity control of the latter rearrangement was obtained from the reactions of (Z)epimeric substrates. The new synthetic approach leading to the 1α-hydroxy epimers complements our previously reported synthesis of the corresponding 1β-epimers, thus producing all stereoisomers of these versatile building blocks efficiently from carvone.
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.
Asymmetric synthesis of 1 α,25-dihydroxyvitamin D3 A-ring precursor starting with 5-tert-butyldimethylsiloxy-2-cyclohexenone
Hareau, Georges P.J.,Koiwa, Masakazu,Sato, Fumie
, p. 2385 - 2388 (2007/10/03)
The A-ring precursor of 1 α,25-dihydroxyvitamin D3 [(E)-4] has been prepared starting from the (5S)-tert-butyldimethylsiloxy-2-cyclohexenone [(S)-1] via eight steps in 19% overall yield, where a catalytic osmium dihydroxylation which sets the stereochemistry of the hydroxyl group at C1 and a regioselective protection of the hydroxy group as a TBS-ether are the key steps. (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.
An asymmetric synthesis of a 1α,25-dihydroxyvitamin D3 A-ring synthon
Chen,Crich
, p. 1945 - 1948 (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
Stereoselective Synthesis of 1α-Hydroxyvitamin D3 A-Ring Synthons by Palladium-Catalyzed Cyclization
Nagasawa, Kazuo,Zako, Yoshiro,Ishihara, Hideki,Shimizu, Isao
, p. 4937 - 4940 (2007/10/02)
Palladium-catalyzed cyclization of 8-bromo-2,8-nonadienoates proceeded stereoselectively to give 1α-hydroxyvitamin D3 A-ring synthons in good yields.
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.
