2-Bromomethyl-l,3-butadiene

Since our last survey, a few methods for joining prenyl bromide (15, R = Br) directly to 2-bromomethyl-l,3-butadiene (9, R = Br, available from isoprene)... 

Reactions with 3-methylbutanal (82) (for ipsenol, 83) or senecio aldehyde (dimethylacrolein, 84, for ipsdienol, 85) were discussed previously (Vol. 4, p. 467). Many further publications on the subject have s peared. Isoprene can be tribrominated, first with bromine in carbon tetrachloride, then with N-bromosuccinimide. This is one route to 2-bromomethyl-l,3-butadiene (9, R = Br), obtained from the tribromide with zinc amalgam reduction, but in fact the tribromide reacted directly with the aldehydes 82 or 84 to give ipsenol (83) or ipsdienol (85). A reagent used for the reaction of 9 (R = Br) with the aldehydes... 

Corey and coworkers , in a synthesis of prostaglandins, prepared diene 34 by alkylation of the lithiodithiane 32 with 2-bromomethyl-l,3-butadiene (equation 41). A synthesis of jasmone (35), in an overall yield of 50%, has been reported by Ellison and Woessner in which the bisdithianylethane 33 was sequentially alkylated, followed by hydrolysis and cyclization (equation 42). A similar route for preparation of 4-hydroxy-2-cyclopenten-l-ones has been reported . This method appears to provide a general route to 1,4-diketones via 1,3-dithianes. 

Noncyclic bis(1,3-diene)s were prepared by the reaction of aromatic diamines with 2 bromomethyl-l 3-butadiene in methanol containing sodium carbonate. The mixture was stirred at room temperature for 2 days under a nitrogen atmosphere. A precipitate formed which was recovered by filtration washed with cold methanol, and dried under vacuum. The bisdiene was dissolved in a methanol acetone (1 4) mixture and reprecipitated from solution by the dropwise addition of water. The mixture was heated until the precipitate redissolved. The solution was subsequently allowed to slowly cool, during which time the monomer precipitated. The bis(1,3-diene) was isolated by filtration and dried under vacuum. 

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See also in sourсe #XX -- [ , ]

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