9-DECYN

Decyn-l-ol (Farchan Labs., Lancaster Synthesis) was used without further purification. Upon addition of 2-decyn-l-ol to the reaction mixture slight warming is observed. The temperature is maintained at 25-30°C using a water bath. 

Reaction of l-bromo-2-butyne with hexylmagnesium bromide to give a mixture containing equal amounts of 1-methyl-1-hexylallene and 2-decyne... 

The bromohydrin is then quantitatively converted to the THP ether, which is added to LiC=CH-ethylenediamine complex in dimethyl sulfoxide to give VII in very high yield. No purification is required in either of these steps. A shorter synthesis of 9-decyn-l-ol (IX) was subsequently developed. An acetylene "zipper" isomerization (42) with sodio-1,3-diaminopropane is used to convert either 3-decyn-l-ol (VIII) or 2-decyn-l-ol into the terminal alkynol IX. Both of these starting alkynols are commercially available and the saving in labor is advantageous for moderate scale production. 

Figure 2. Proposed orientation of the alkyne-rhodium triphenylphosphine complex between the silicate sheets of hectorite, prior to hydrogen transfer (top) the iidtti, obtained by subtracting the thickness of the silicate sheet ( 9.6 A) from the observed 001 X-ray reflection, is a measure of the interlayer thickness. The critical dimension of 2-decyne (bottom) is defined as the minimum distance which must be spanned by the molecule when the C C axis is perpendicular to the silicate...

Figure 6. Conformer distribution of 2-decyn-l-ol based on the maximum geometric distances in the molecules (Lmax (A) on the abscissa]. The number of quintals is seven.

B. Acetylenes that destroy cytochrome P450 by other mechanisms 2-Hexyne 2-Decyne... 

C24K is a moderately active catalyst for hydrogenation of alkenes. It is a very efficient catalyst for isomerization of cw-stilbene to trcnj-stilbene. It is also effective for isomerization of alkynes 2-octyne-> 1-octyne (86% yield). An allene is a probable intermediate 2-decyne -> 1-decyne (207o) and 1,2-decadiene (9%,). Potassium alone also effects these isomerizations, but only at higher temperatures. Benzene is slowly converted into biphenyl when in contact with C24K in refluxing cyclohexane. This reaction has also been reported for CgK in DMF at 20 (61%, yield).=... 

The asymmetric allylboration of 2-decynal (18) provides addition products 19-21 in 72%, 72% and 58% ee with reagents 1-3, respectively. In contrast, the allylborations of 2-dec5mal-dicobalt hexacarbonyl complex 22 with 1-3 followed by decomplexation with Fe(N03)3 in EtOH at room temperature provides adducts 19-21 with improved%ee s of 92%, 96% and 86%, respectively, in 85-95% yield. 

Problem 7.9 Consider the regioselectivity of the hydration of 2-decyne. Write the products of the reaction. Predict the percentage of each compound in the product mixture. 

The initial hydration of an alkyne places the hydroxyl group on the more substituted carbon atom. This carbon atom is the eventual site of the carbonyl group. In 2-decyne, both C-2 and C-3 are substituted to the same degree. C-2 is bonded to a methyl group C-3 is bonded to a heptyl group. As a consequence, hydration can occur either of two ways, and two products, 2-decanone and 3-decanone, are formed. 

Figure 6. (A) proposed orientation for the reactive RhH2L2 -alkyne intermediate in the clay interlayer, (B) the 2-decyne critical dimension or minimum interlayer distance required to achieve a reactive configuration.

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