Boranes hydrocarbons, synthesi

The synthesis of small strained cyclophanes attracted the attention of chemists for many years because the forced proximity of atoms leads to unusual chemical and physical properties. Using the Suzuki reaction to couple a three-legged borane intermediate derived from a triallylsilane 256 to 1,3,5-tribromobenzene, the analogue of Pascal s hydrocarbon was obtained in a single step <19940M3728>. This strategy has been applied to the synthesis of 257 (4% yield) from tris-borabicyclo[3.3.1]nonane (9-BBN) adduct of methyltriallylsilane 256 and 1,3,5-tribromobenzene (Scheme 43). 

USE In Organic synthesis, especially in the production of hydrocarbons, alcohols, ketones, organic adds, amines, silicones, boranes. 

If similar processes could be developed at energy conversion efficiency levels that are comparable to the present day SMR-based NH3 synthesis plants, then it would be possible to realize a major reduction in the production costs of ammonia-borane complex. We note that a concept similar to that discussed above has already been developed for nitric acid synthesis process based on boron nitride analogous to the Haber-Bosch route for nitric acid production from NH3. Finally, recent results have shown that unusual parallel behavior exists between hydrocarbons and their corresponding B-N analogues. Thus, hydrogenation of benzene to cyclohexane may also provide a model for the reformation of borazine to other amine-boranes. 

Another method for preparing functional Ziegler-Natta polymers is to use an organoborane mediated synthesis. This method has been extensively studied and reviewed by Chung . The success of this technique results from these factors (a) trialkyl boranes are Lewis acids, which are stable to Z-N catalysts, (b) they are soluble in Z-N (hydrocarbon) solvents, (c) they are remarkably versatile synthons for a variety of functional groups. In this case, borane functional alpha olefin monomers (31) are polymerized to polyboranes which can be hydrolyzed to a variety of functional groups. 

Non-fluxional vinylic boranes do not react with carbonyl compounds. Nevertheless, the vinylic borane 29 reacts with acetone (2 h under reflux) yielding the Z-isomer of the homoallylic borinic ester 30b. The cw-configuration of the reaction product 30b corresponds to the following sequence of transformations (Scheme 2.11). The [1,7]-H shift in the vinylic borane 29 gives the allylic Z, Z-isomer 28d which immediately reacts with acetone before the equilibrium among the allylic isomers is established. On the other hand, cyclopentanone reacts directly with 29 under mild conditions yielding Z, Z-1,3,5-heptatriene 31 and borinic ester 32 (Scheme 2.12). Apparently 29 reacts with the enol form of cyclopentanone, and a direct splitting of the B-Q ,2 bond takes place. Similar reaction of 29 with acetic acid was used for the preparative synthesis of previously unknown hydrocarbon 31 (Scheme 2.12) [35]. 

Via intermediates Synthesis of hydrocarbons from ethylene derivatives via boranes A new general coupling reaction... 

Silver nitrate potassium hydroxide Synthesis of hydrocarbons from boranes... 

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