67619-74-3

Upstream product

• 90079-82-6 (1R,6R)-14-epi-1-hydroxy-9,10-secocholesta-5⁽¹⁰⁾,6,7-triene 
• 67670-81-9 (1R,10R)-(5Z,7Z)-1-hydroxy-9,10-secocholesta-5,7,14-triene 
• 67632-48-8 (1R,6R)-1-hydroxy-9,10-secocholesta-5⁽¹⁰⁾,6,7-triene 
• 67-97-0 vitamin D₃ 
• 56671-84-2 3-iodo-2-methylcyclohexenone 
• 67619-75-4 de-A,B-8α-ethynyl-8β-cholestanol 
• 74398-26-8 (6R)-9,10-secocholesta-5⁽¹⁰⁾,6,7-triene-1-one 
• 74398-25-7 de-A,B-8α-ethynyl-8β-cholestanol benzoate 
• 67619-70-9 2-methyl-3-iodocyclohex-2-en-1-ol 
• 75154-95-9 (1R,6Z)-1-Hydroxy-9,10-secocholesta-5⁽¹⁰⁾,6,8-⁽¹⁴⁾-triene 
• 75154-94-8 (6Z)-9,10-secocholesta-5⁽¹⁰⁾,6,8⁽¹⁴⁾-trien-1-one 
• 66251-18-1 Grundmann's ketone 
• 67619-71-0 1-tert-butyldimethylsiloxy-2-methyl-3-iodocyclohex-2-ene 
• 1193-55-1 2-methylcyclohexane-1,3-dione 

Downstream Products

• 75154-95-9 (1R,6Z)-1-Hydroxy-9,10-secocholesta-5⁽¹⁰⁾,6,8-⁽¹⁴⁾-triene 
• 67670-81-9 (1R,10R)-(5Z,7Z)-1-hydroxy-9,10-secocholesta-5,7,14-triene 

Relevant academic research and scientific papers

7,8-Cis geometric isomers of the steroid hormone 1α,25-dihydroxyvitamin D3

The syntheses of the previously unknown, sterically hindered geometric isomers 3 and 4 of the steroid hormone 1α,25-dihydroxyvitamin D3(1,1,25) have been achieved for the first time. The stereoselective synthesis of the vinylallene precursor 23a was achieved by the Inanaga method, Pd(0)-Sm(II)-iPrOH reduction of propargyl benzoate 33. The latter observation reveals that the Inanaga propargyl ester to allene transformation is in fact stereoselective (～10:1), involving a formal anti-SN2′ displacement of benzoate by hydrogen. Highly stereoselective (50:1, 85% yield) (1,5)-hydrogen shift of vinylallene 23a to the sterically hindered 7,8-cis isomer of the hormone 1, namely, 3, was achieved by the Shibasaki method using (naphthalene)tricarbonylchromium (22, (np)(CO)3Cr). By examining this chromium-(0)-mediated isomerization on all four diastereomeric vinylallene analogue systems 6a,b and 7a,b, all of which resulted highly selectively (50:1) in hindered 7,8-cis geometric isomers, new stereomechanistic information concerning the Shibasaki type 1,5-shift has also emerged. By cheleotropic addition-extrusion of sulfur dioxide on 3, there was obtained the final unknown geometric isomer of 1, 5,6-trans-7,8-cis-1,25 4; this result parallels the known transformation of 1 to 2. Although the vinylallene 23a can be thermally rearranged via a [1,5]-sigmatropic hydrogen shift to the natural hormone 1, the yield and selectivity are modest. By contrast, one-way triplet photosensitized isomerism of the now readily available 7,8-cis-isomer 3 results primarily in the natural hormone 1 in good yield and selectivity. Taken collectively, these observations reveal that the synthesis of all four geometric isomers 1-4 can be achieved from a single precursor, the vinylallene 23a. Comparative biochemical evaluation, in vitro, of the four geometric isomers in terms of their ability to bind to the chick intestinal receptor reveals that 7,8-cis isomerism (3 and 4) significantly suppresses their ability to bind receptor (2% each versus 100% for the hormone 1,25).

Thermal Rearrangement of Vinylallenes: Synthesis of 3-Deoxy-1α-hydroxy-14-epiprevitamin D3

The lithium salt of the terminal allene 12a was reacted with keto enol ether 13 to give the vinylallenones 8a(6R) and 9a(6S).On reduction with sodium borohydride, 8a afforded vinylallenols 8b(1R,6R) and 8c(1S,6R); similarly 9a gave 9b(1R,6S) and 9c(1S,6S)

Studies on Vitamin D (Calciferol) and Its Analogues. 18. The Vinylallene Approach to the 1-Hydroxyvitamin D System. New Sigmatropic Reactions in the Vitamin D Series

The thermally induced -sigmatropic hydrogen shift of the diastereomeric vitamin D type vinylallenols 6a (1R,6R), 6b (1R,6S), 7a (1S,6S) and vinylallenols 5a (6R) and 5b (6S) were studied.The 1S,6S (7b) and 1R,6R(6a) alcohols afforded ca. 60percent yi