2- Bromomethyl butadiene

Silverstein et al. (51, 136) began their synthesis of racemic ipsenol by coupling 2-bromomethyl butadiene (237) with the anion of the dithiane derivative (236) of 3-methyIbutanal (235) (Scheme 47). Desulfurization of (238) and reduction of ketodiene (239) gave the desired alcohol (240). 

In the synthesis of the taxol skeleton, two successive applications of the reaction on a masked equivalent for 2,3-bis(bromomethyl)-l,3-butadiene are the key steps59. 

The synthesis of N-phenyl-1,3,4,6-tetrahydrothieno(3,4-c)-pyrrole-2,2-dioxide (II) was carried out by reacting aniline with 3,4-bis(bromomethyl)-2,5-dihydrothiophene-l,1-dioxide (I). The latter compound was synthesized by the bromination of the cycloaddition product, prepared from 2,3-dimethyl-l,3-butadiene and sulfur dioxide (17). 

An alternative preparation of the exocyclic diene (III) was attempted by first thermally decomposing the bromosulfone (I) to yield 2,3-bis(bromomethyl)-1,3-butadiene VI, which, in turn, was allowed to react with aniline following the procedure described by Gaoni (19). 

Hegedus and Varaprath studied the reactions of various bromodienes with Ni(CO)4 and with bis(cyclooctadiene)nickel. l-Bromo-2,5-hexadiene and 2-bromomethyl-1,3-butadiene give the stable products 62 and 63, respectively, which resemble allyl nickel halides in their properties (217). Similar compounds had been prepared several years previously from geranyl halides (218). l-Bromo-2,4-pentadiene and l-bromo-2,4-hexadiene, however, formed intractable materials which could not be isolated and purified. In these cases the red color of the solution which was first produced faded and NiBr2 was deposited. The desired compounds, however, could be generated in situ at — 30° C and used in coupling reactions with aryl, alkenyl, and allyl halides (217). 

DIELS-ALDER REACTIONS Allylidenecy-clopropane. 1 -Bromo-2-chlorocyclopro-pene. 2-Bromomethyl-3-(trimethylsilylme-thyl)butadiene. Camphor-10-sulfonic acid. 

If 2,3-bis(bromomethyl)-1,3-butadiene is reacted with FeifCO) the products XLI, XLII and XLIII are formed in 11 %, 7.5% and 2% yields, respectively . 

Doubly prototropic furans are known. The simplest (125) is unstable but can be obtained in 15% yield by treating tetra(bromomethyl)ethene with sodium hydroxide. The product lacks an IR band at 1725 cm-1 that had been noted in a different preparation, now thought to indicate contamination by acetic acid.242 Another such compound has structure 126, remarkable because the butadiene chromophores react strongly across the ring.243 No special sensitivity is reported, and aromatization would of course be prevented because of the inordinate strain imposed according to Bredt s rule. The plant Limlera obtusiloba Blume elaborates as a main component of its leaves a furan derivative known as obtusilactone244 structure 127 possesses... 

Dtittmann, H., and Weyerstahl. P.. ], 3-Butadiene-2-carboxylic acids starting from the Wittig salt of 2-(bromomethyl)acrylic acid. Chem. Ber., 112, 3480, 1979. 

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... 

Although several systems have been evaluated to determine the structure of the ring formed in cyclopolymerization, very little work has been reported on the original cyclopolymer reported by Butler ( 7) that was obtained from N,N-dimethyldiallyl-ammonium bromide or the chloride. Consequently, we undertook a study of a five-membered quaternary ammonium polymer, poly(l,l, 3,4-tetramethyl-3-pyrrolinium bromide) as a model system. N,N-dimethyl-3,4-dimethylenepyrrolidinium bromide (6 ) was prepared by reacting dimethylamine with 2,3-bis(bromomethyl)-l,3-butadiene (5). In addition to the bromide salt (6), the iodide salt was also prepared by reacting 2,3-bis(bromomethyl)-l,3-butadiene... 

Thiazolin-4-one derivative 29 in hydrazino-hydrazono tautomeric equilibrium is synthesized by cyclization of l,2-diaza-l,3-butadiene 27 with aryl thioamide 28. Subsequent hydrolytic removal of the NH-Boc-hydrazo protecting group provided 5-acetyl-4-hydroxythiazole derivative 30a, which undergoes a-bromination to give a-bromomethyl ketone 30b. This bromide is used to prepare polyfunctionalized 4,5 -bithiazol-4 -ol derivatives via the Hantzsch thiazole synthesis <04SL2681>. 

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. 

CgHgBrfl, Tetrakis(bromomethyl)methane (gas-ed), 42B, 1024 CsHgClfl, Tetrakis(chloromethyl)methane (gas-ed), 40B, 1135 CgHgO, trans-1-Methoxy-1,3-butadiene (gas-mw), 43B, 1485 CsHe02f Acetylacetone (gas-ed), 37B, 691 38B, 1065 CgHgCla, 1, 1, 1-Tris(chlorom.ethyl)ethane (gas-ed), 40B, 1135 C5H10, 2-Methyl-1-butene (gas-ed), 33B, 531... 

Another dehalogenatlve formation of a trimethylenemethane complex, which involves a dimerization, starts from 2-(bromomethyl)-l,l-butadiene (7), which gave dinuclear complex 8 in 36% yield by stirring with Fe2(CO)g in hexane for 24 h (Scheme 10.4) [16]. Lillya et al. pointed out that the allylic cation derived from 7... 

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