29569-75-3

Upstream product

• 108-05-4 vinyl acetate 
• 32635-27-1 (+/-)-3-ethynyl-4-methylcyclohex-3-en-1-ol 
• 66901-50-6 (2S,5S)-5-hydroxy-2-methylcyclohexan-1-one 
• 950488-12-7 (S)-(-)-6-methylcyclohex-2-en-1-one 
• 145640-36-4 1-((tert-butyldiphenylsilyl)oxy)-3-(2,2-dibromoethenyl)-4-methylcyclohex-3-ene 
• 145640-32-0 5-((tert-butyldiphenylsilyl)oxy)-2-methylcyclohex-1-enecarboxaldehyde 
• 150-76-5 4-methoxy-phenol 
• 130745-59-4 4-<(tert-Butyldiphenylsilyl)oxy>cyclohexanone 
• 69125-55-9 4-hydroxy-1-methoxy-1-cyclohexene 
• 13482-22-9 4-hydroxycyclohexanone 
• 145640-38-6 1-((tert-butyldiphenylsilyl)oxy)-3-ethynyl-4-methylcyclohex-3-ene 

Downstream Products

• 1173-13-3 previtamin D₃ 

Relevant academic research and scientific papers

Tunneling in tocopherol-mediated peroxidation of 7-dehydrocholesterol

The peroxidation of 7-dehydrocholesterol (7-DHC), a biosynthetic precursor to vitamin D3 and cholesterol, has been linked to the pathophysiology of Smith-Lemli-Optiz syndrome (SLOS), a devastating human disorder. In SLOS, 7-DHC plasma and tissue levels are elevated because of defects in the enzyme that convert it to cholesterol. α-Tocopherol can mediate the peroxidation of 7-DHC under certain circumstances and this prompted us to investigate the kinetic isotope effect (KIE) during this process. Thus, 9,14-d2-7-DHC was synthesized using a photochemical cyclization of deuterium-reinforced previtamin D3 (retro to its biosynthesis). Subsequently, we carried out co-oxidation of 9,14-h2-25,26,26,26,27,27,27-d7- and 9,14-d2-7-DHC in the presence of α-tocopherol under conditions that favor TMP. By monitoring the products formed from each precursor using mass spectrometry, the KIE for the hydrogen (deuterium) atom removal at C9 was found to be 21 ± 1. This large KIE value indicates that tunneling plays a role in the hydrogen atom transfer step in the tocopherol-mediated peroxidation of 7-DHC.

Selective acylation of A-ring precursors of vitamin D using enzymes in organic solvents

Whereas Chromobacterium viscosum lipase (CVL) catalyzes selectively the acylation of the C-5 hydroxyl of the three stereoisomeric vitamin D A-ring precursors 2a, 3a and 3b, only the C-3 hydroxyl of the fourth stereoisomer 2b is acylated under the same conditions in organic solvent. In a convenient application, the racemic vitamin D A-ring precursor 4, possessing only the C-5 hydroxyl, was resolved using suitable conditions identified from the studies of 2 and 3.

Thermal -Sigmatropic Shift of Previtamin D3 to Vitamin D3: Synthesis and Study of Pentadeuterio Derivatives

Specifically pentadeuteriated previtamin D3 11 has been synthesized to impart thermal stability to the otherwise labile material.A 12-step synthesis of the trideuteriated A-ring 14b from p-methoxyphenol was developed and employed the addition of (methyl-d3)magnesium iodide to either the keto thiomethylene intermediate 23 or the keto dioxane 27.The enantiomerically pure trideuterio A-ring (-)-14b was then coupled with the deuteriated CD fragment 13b followed by hydrogenation to afford pentadeuteriated previtamin D3 11.A primary deuterium kinetic isotope effect (KIE) study of the -sigmatropic hydrogen migration in the conversion of previtamin D3 to vitamin D3 indicated a more "normal" primary deuterium isotope effect (as compared to a previously reported literature value of ca. 45).At 80 deg C, a kH/kD for the previtamin D3 to vitamin D3 isomerization was determined to be ca. 6.2.At 25 deg C, this -sigmatropic hydrogen migration proceeds with a kH/kD of ca. 11.4.The revisible, first-order -sigmatropic hydrogen shift of previtamin D3 to D3, determined over the temperature range 60.1-85.5 deg C is characterized by the following activation parameters: log AH = 8.8 and EaH = 19.6 kcal/mol.Deuteriated pre-D3, which rearranges over this temperature range, is characterized by the activation parameters log AD = 9.5 and EaD = 21.9 kcal/mol.