An efficient synthesis of 4α- and 4β-hydroxy- 7-dehydrocholesterol, biomarkers for patients with and animal models of the Smith-Lemli-Opitz syndrome.
A highly efficient and improved method for the preparation of stereoisomeric 4α- and 4β-hydroxy-7-dehydrocholesterol has been developed. These oxysterols are atypical precursors of cholesterol found to be present in increased concentrations in brain, liver, and serum of animals treated with AY9944, an inhibitor of 3β-hydroxysterol-Δ(7)-reductase (Dhcr7). AY9944 -treated rats are considered a model for Smith-Lemli-Opitz syndrome (SLOS). The principal reactions involved were (1) cis-4α,5α-dihydroxylation of the allylic 3β-acetoxy-Δ(4) intermediate with in situ generated RuO4 and subsequent dehydration with SOCl2, (2) direct 4β-hydroxylation of cholesterol with selenium dioxide, and (3) regioselective dehydrogenation at C-7/-8 of the resulting 4α- and 4β-hydroxylated derivatives with 1,3-dibromo-5,5-dimethylhydantoin/azobisisobutyronitrile, followed by tetrabutyl ammonium bromide/tetrabutyl ammonium fluoride. Chemical instability of these 4-hydroxylated 7-dehydrocholesterols when exposed to UV light, heat or in an acidic medium is briefly discussed.
Department of Chemistry, College of Humanities & Sciences, Nihon University, Sakurajousui, Setagaya, Tokyo 156-8550, Japan.
Hiroaki
H
Kawamoto
Yuusuke
Y
Ohmori
Masamitsu
M
Maekawa
Miki
M
Shimada
Nariyasu
N
Mano
Takashi
T
Iida
D000818:Animals; D015415:Biomarkers / Q000737:chemistry / Q000378:metabolism; D003684:Dehydrocholesterols / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism*; D004195:Disease Models, Animal; D006801:Humans; D019082:Smith-Lemli-Opitz Syndrome / Q000139:chemically induced / Q000378:metabolism*; D001371:trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride
D015415:Biomarkers; D003684:Dehydrocholesterols; D001371:trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride; C016705:7-dehydrocholesterol
4α-hydroxy-7-dehydrocholesterol; 4β-hydroxy-7-dehydrocholesterol; 7-dehydrocholesterol; Biomarker; Oxysterol; Smith–Lemli–Opitz syndrome