3- Octen-l-yne

Alkynes are generally more reactive than alkenes as enophiles in both inter- and intra-molecular ene reactions. - 6-Octen-l-yne (100) cyclizes to l-methylene-2-vinylcyclopentane (101) on brief heating at 400 Dehydrolinalool (102) undergoes an ene reaction at 200 C to give (103) in quantitative... 

The submitters report bp 86-87°C (0.3 urn). (E)-1-Hexenyl-1,3,2-benzodioxaborole is quite air stable, but it can slowly hydrolyze to boronlc acid and turn brown on repeated use in air. The submitters recommend storing it at refrigerator temperature In a bottle purged with nitrogen and capped with a rubber septum. Alternatively, the crude 1-hexenyl-1,3,2-benzodioxaborole can be used for the next coupling reaction without purification. In this case, the unreacted 1-hexyne should be removed under reduced pressure (0.1 mn for 30 min), because it also reacts with (Z)-6-bromostryrene to afford (lZ)-l-phenyl-l-octen-3-yne. In this manner the expected diene was obtained in a yield of 86%. 

The reaction sequences of Scheme 21 are supported by the following facts (i) the CAD spectrum of the product of H2 loss (40 ) is identical to that of authentic Fe(l-octene-6-yne) (ii) deuterated 2-octynes undergo regiospecific H2 and C2H4 losses, largely involving the triple bond-remote positions C(7) and C(8). ... 

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