Cycloadducts of ergosterol with azo-type dienophiles, and their chemical reactivities was written by Georghiou, Paris E.;Just, George. And the article was included in Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1972-1999) in 1973.SDS of cas: 28322-40-9 This article mentions the following:
Ergosteryl acetate (I) with 3,6-pyridazinedione gave the adduct (II, R = CH:CHCHMeCHMe2). I with 1,4-phthalazinedione and 4,5-dihydro-3,6-pyridazinedione gave analogous adducts. II (R = CH:CHCHMeCHMe2) with O3 gave II (R = CH:CHCH2CHMe2). In the experiment, the researchers used many compounds, for example, Isopentyltriphenylphosphonium bromide (cas: 28322-40-9SDS of cas: 28322-40-9).
Isopentyltriphenylphosphonium bromide (cas: 28322-40-9) belongs to organobromine compounds. Most organobromine compounds, like most organohalide compounds, are relatively nonpolar. 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.SDS of cas: 28322-40-9
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary