《Boron tribromide as a reagent for anti-Markovnikov addition of HBr to cyclopropanes》 was published in Chemical Science in 2020. These research results belong to Gieuw, Matthew H.; Chen, Shuming; Ke, Zhihai; Houk, K. N.; Yeung, Ying-Yeung. Electric Literature of C4H7Br The article mentions the following:
Although radical formation from a trialkylborane is well documented, the analogus reaction mode is unknown for trihaloboranes. The generation of bromine radicals from boron tribromide and simple proton sources, such as water or tert-butanol, under open-flask conditions was discovered. Cyclopropanes bearing a variety of substituents I (R1 = Ph, naphthalen-2-yl, CN, etc.; R2 = H, Me, Ph, methoxycarbonyl, etc.; R3 = H, Ph) were hydro- and deuterio-brominated to furnish anti-Markovnikov products (R1)(R2)C(R4)CH2CH(R3)Br (R4 = H, D) in a highly regioselective fashion. NMR mechanistic studies and DFT calculations point to a radical pathway instead of the conventional ionic mechanism expected for BBr3. In the experimental materials used by the author, we found (Bromomethyl)cyclopropane(cas: 7051-34-5Electric Literature of C4H7Br)
(Bromomethyl)cyclopropane(cas: 7051-34-5) is used as a synthetic building block for the introduction of the cyclopropylmethyl group. It was also used in the synthesis of 1,4-dienes via iron-catalyzed cross-coupling with alkenyl Grignard reagents.Electric Literature of C4H7Br
Referemce:
Bromide – Wikipedia,
bromide – Wiktionary