Bromination of isoprene

Polar, Functionalized Diene-Based Materials. 1. Bulk, Solution, and Emulsion Free Radical Polymerization of 2-Cyanomethyl-1,3-butadiene

“…The first step, 1,4-addition of bromine to isoprene, gave 1,4-dibromo-2-methyl-2-butene (I) in nearly quantitative yield. 15 Low reaction temperatures (<-20°C) were necessary to avoid the production of other isomers. Subsequent dehydrobromination using 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU) gave compound II.…”

“…Using varying amounts of THF (Table 3, examples 5-7), the chain transfer constant in THF was calculated to be 1.15 × 10 -3 , assuming the solvent is the main chain transfer agent. Other polar solvents, acetone, acetonitrile, and nitromethane, were also used ( Table 3, examples [15][16][17]. In each case, polymers with polydispersities larger than 2.6 were obtained.…”

Geminal Difunctionalization of Alkenylidene-Type Carbenoids by Using Interelement Compounds

“…We next applied the reaction to an unsubstituted carbenoid, 1-bromo-1-lithioethene (4 b), available by treatment of vinyl bromide (3 b) with lithium 2,2,6,6-tetramethylpiperidide (LiTMP), and isolated 1,1-diborylethene 5 b (or 6 b) in high yields (Table 1, entries 3 and 4, respectively). As (E)-1,4-dihalo-2-butene is known to give predominately (Z)-1-halobutadiene, [11] (E)-1,4-dichloro-2-butene (3 c) was treated with two equivalents of LiTMP at À 90 8C to stereoselectively give (Z)-1-chloro-1-lithio-1,3-butadiene (4 c), [12b] which was allowed to react with 1 (or 2) and afforded dienyldiborane 5 c (or dienyl(silyl)borane 6 c) in high yields (Table 1, entries 5 and 6, respectively). Noteworthy is that the stereochemistry of 6 c was exclusively E [13] in accord with the configuration of 4 c and with a mechanism involving stereoselective formation of an intermediate borate complex followed by stereospecific 1,2-migration.…”

Synthesis oftrans-4-Amino-1-hydroxy-2-methyl-2-butene from Isoprene

“…In the second method (route B, Fig. 1 was treated with sodium hypochlorite solution to afford trans-l-t-butoxy-4-chloro-2-methyl-2-butene (8). With the Gabriel reaction, 8 gave a phthalimide derivative (9).…”