1- Heptyne, 1-bromo

In the flask were placed 0.40 mol of dry, powdered copper(I) cyanide, 9 g of anhydrous lithium bromide (note 1), 50 ml of dry THF and 0.30 mol of l-bromo-2--heptyne (prepared from the corresponding alcohol and PBrs in diethyl ether, see VIII-2, Exp. 10). The mixture was heated until an exothermic reaction started, which occurred at about 80°C. The solid dissolved gradually. The mixture was kept... 

CH2 =CHCH2CsCR, add only two molecules of methanol under the same conditions to yield 5,5-dimethoxy-l-alkenes, CH2 =CHCH2CH2C(OCHj)2R. Reaction of 1-chloro- or 1-bromo-heptyne, C, H,C = CX, in the same way gives the corresponding 1-halo-2,2-dimethoxyheptanes, CjH C(OCHj)2CH2X, in 30 and 60% yield, respectively. ... 

PBr3 added at a rate to maintain refluxing to a soln. of 2-heptyn-l-ol and a small amount of pyridine in dry ether, then stirred and heated for another 2 hrs. —l-bromo-2-heptyne. Y 72%.—None of the desired product was obtained when 1 equivalent of pyridine was used. (F. e. s. M. S. Newman and J. H. Wotiz, Am. Soc. 71, 1292 (1949).)... 

The addition of HBr to an alkyne can be facilitated by using acetyl bromide (CHsCOBr) and alumina instead of aqueous HBr. Acetyl bromide acts as an HBr precursor by reacting with the alumina to generate HBr. For example, 1-heptyne can be converted to 2-bromo-l-heptene in good yield using this method ... 

We developed several simple routes for the syntheses of pure isomers of CLA. The synthesis via an enyne-substructure (Fig. 3.6) required r-l-bromo-l-heptene [5] and l-(2 -tetrahydropyranyloxy-y)-10-undecyne [2] as building blocks. Cft-l-bromo-1-heptene was prepared by reaction of commercially available 1,3,2-benzodioxaborole with 1-heptyne [3], yielding the 1-alkenylboronic acid ester [4] after heating for 2 h. No solvent was required. The f 2 j-configurated double bond formed during the... 

The reaction of l-bromo-2-heptyne with zinc in the presence of 2,2-dimethylpropanal [67], however, did yield the allenic derivative as the main product together with small amounts of the acetylenic compound ... 

The oxypalladation-reductive elimination of 3-pentynoic acid with 1-bromo-l-heptyne has also been described (Scheme 22). However, 4-methyl-4-(l-heptynyl)-5//-furan-2-one was isolated in low yield. Substitution of 1-iodo-l-heptyne for 1-bromo-l-heptyne resulted in the formation of the diyne derivative as the only reaction product. Most probably, the diyne derivative is formed via Pd-catalyzed coupling of the l-halo-l-aUcyne. 

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