New syntheses of 1α,25-dihydroxycholesterol was written by Fuerst, Andor;Labler, Ludvik;Meier, Werner. And the article was included in Helvetica Chimica Acta in 1982.Computed Properties of C23H26BrP This article mentions the following:
1α,25-Dihydroxycholesterol was prepared via 5 convergent syntheses by combining C21– or C22-steroids with C4– or C5-side-chain building blocks. Thus, pregnene I (R = tetrahydro-2-pyranyl, R1 = CH2O3SC6H4Me-H) was combined with the dioxolane II, PhSO2CH2CH2CMe2OR2 (R2 = tetrahydro-2-pyranyl) and HCCCMe2OR2 and I (R = Ac, R1 = CHO) was combined with Ph3P:CHCH2CMe2OH. Also, pregnenone III was condensed with phosphorane IV. In the experiment, the researchers used many compounds, for example, Isopentyltriphenylphosphonium bromide (cas: 28322-40-9Computed Properties of C23H26BrP).
Isopentyltriphenylphosphonium bromide (cas: 28322-40-9) belongs to organobromine compounds. Bromine is more electronegative than carbon (2.9 vs 2.5). Consequently, the carbon in a carbon–bromine bond is electrophilic, i.e. alkyl bromides are alkylating agents. Many of the alkyl bromine derivatives are excellent alkylating agents since bromides are good leaving groups. Tribromides, like tetrabutylammonium tribromide, are used as a solid source of bromine. N-bromosuccimide (NBS) is used for the selective bromination of allylic bonds.Computed Properties of C23H26BrP
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary