1- Bromo-5-methyl-3-hexyne

Preparation of Diethyl (1-Methyl-2-Pentynyl) Malonate To a solution of 2B.6 g of sodium in 430 ml of absolute ethanol were added 200 g of diethyl malonate. About half of the alcohol was removed by distillation in vacuo, and thereafter a solution of 200 g of 2-bromo-3-hexyne in 100 ml of anhydrous ether was added slowly to the reaction mixture. 

The heat of reaction brought about refluxing during the addition of the 2-bromo-3-hexyne, and when the addition was complete the reaction mixture was heated to refluxing for a further period of 30 minutes. A sufficient amount of water was then added to the reaction mixture to dissolve the sodium bromide which had formed, and the only organic layer was separated, washed with water and dried over anhydrous magnesium sulfate. The dried organic layer was then fractionally distilled under reduced pressure, and the diethyl (1-methyl-2-pentynyl) malonate formed in the reaction was collected at about 117° to 120°C at the pressure of 2 mm of mercury. 

Preparation by reaction of 6-bromo-l-hexyne with 5-allyl-2,4-dihydroxyace-tophenone in the presence of potassium carbonate and potassium iodide in refluxing methyl ethyl ketone (15-20%) [2671,2678,2679],... 

Butyl-5-methyl 2-Bromo-5-methylacetanilide l-(Tri-n-butyl-stannvl)hexyne, (1) Pd(PPh,)4, (2) PdCl lCHjCN) 81,77 [1]... 

C7H12 3-methyl-1-hexyne 40276-93-5 15.221 134.695 1,2 11570 C7Hl3Br trans-1-bromo-1-heptene 53434-74-5 17.201 154.389 1,2... 

Dien-4-ynes 136 (R -R = alkyl) are produced from propargylic carbonates 135 and terminal alkynes in the presence of a palladium-phosphine complex and copper(I) iodide. The linear co-dimerization of terminal acetylenes and 1,3-dienes is catalyzed by ruthenium(cyclooctadiene)(cyclooctatriene)(trialkylphosphine) (alkyl = Et, Bu or octyl) thus 1-hexyne and methyl penta-2,4-dienoate give a mixture of the eneynes 137 and 138. Coupling of octa-l,7-diyne (139) with the acetylenic bromo acid 140 in aqueous THF-methanol containing butylamine, hydroxylamine hydrochloride and copper(I) chloride gave a mixture of the triynyl acids 141 and 142. ... 

Now, let s draw the forward scheme. Radical bromination of 2-methylbutane produces the tertiary alkyl hahde, selectively. Then, elimination with NaOEt, followed by awti-Markovnikov addition (HBr / peroxides), and then elimination with iert-butoxide, followed by another awri-Markovnikov addition (HBr / peroxides) produces l-bromo-3-methylbutane. This alkyl hahde will then undergo an Sn2 reaction when treated with an acetylide ion to give 5-methyl-1-hexyne. Ozonolysis of this terminal alkyne cleaves the CC triple bond, producing the carboxylic acid. Deprotonation (with NaOH) produces a carboxylate nucleophile that subsequently reacts with bromomethane in an Sn2 reaction to give the desired ester. 

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