2- Benzyloxy-1-propene

T. Mukaiyama, M. Ohshima, and M. Murakami, 2-Benzyloxy-propene A novel protective reagent of hydroxyl groups, Chem Lett 265 (1984) T. Mukaiyama, M. Ohshima, H. Nagaoka, and M. Murakami, A novel acid-resistant acetal-type protective group for alcohols, Chem. Lett 615 (1984). 

Various carbonyl compounds, such as ( )-3-(benzyloxy)propenal (30), do not react with cyclo-propylidenetriphenylphosphorane. However, the addition of a phase-transfer catalyst can greatly influence the progress of a reaction. Thus, yields obtained from Wittig-type reactions with cyclopropylidenetriphenylphosphoranes are greatly improved by the addition of tris[2-(2-methoxyethoxy)ethyl]amine (TDA-l). The failure of ( )-3-(benzyloxy)propenal to react with cyclopropylidenetriphenylphosphorane was converted into a useful reaction when 10 mol % of TDA-1 was utilized. ... 

Benzyloxy-2-propenylchromium reagents are formed by the action of iodotrimethylsilane and chromium(II) chloride on 3,3-bis(benzyloxy)-l-propene in the presence of aldehydes, affording derivatives of anti-diols with good diastereoselectivity13. 

Chelation control, as indicated in 5, is also a suitable model for rationalizing the stereochemical outcome of titanium tetrachloride mediated additions of 3,3-dimelhyl-2-trimethylsilyl-oxy-l-butenc (6) or l-methoxy-2-methyl-l-trimethylsilyloxy-l-propene (7) to 3-benzyloxy-2-methylpropanal (4). In both cases, there is almost exclusive formation of the chelate-controlled product (95 5 and >97 3, respectively)13. 

The combination of the enantiomerically pure 7V-methylephedrine derived silylketene acetal l-[(l/ ,2S)-2-dimethylamino-1-phenylpropoxy]-l-triniethylsilyloxy-l-propene with the chiral aldehyde (,R)-3-benzyloxy-2-methylpropanal leads, after reduction with lithium aluminum hydride, to the formation of a single 1,3-pentanediol 9 ( matched pair ). 

The (Z)-configuration of the enol ether however is a prerequisite for both high. yyn-selecting and high optical purity of the products23. When, on the other hand, (Z)-2-benzyloxy-l-ethyl-thio-l-trimethylsilyloxy-l-propene is allowed to react with 2-propional in the presence of the diamine 2, the anti-aldol product is obtained in 92% ee42. 

Propene 2-(4-Benzyloxy-phenyl)-1,l-difluoro- ElOb, 298f. 

Alcohols t-Butyldiphenylchlorosilane, 2-Benzyloxy-l-propene. Bis(iso-propylthio)boron bromide. t-Butylmethox-yphenylsilyl bromide. 2,3-Dichloro-5,6-di-cyano-l,4-benzoquinone. Mercury(II) chloride.4,4, 4 -Tris(4,5-dichlorophthalam-idoltrityl bromide. Tetramethylguanidine. Aldehydes Lithium moipolide. Organotitan-ium compounds. 

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