Synthesis geospecific

A soln. of the startg. m. and 4 equivalents ketal heated ca. 8 hrs. at 100° in toluene containing 2,4-dinitrophenol as catalyst, and the intermediate ketone treated at 0° with NaBH4 in methanol > product. Y up to 81% purity 98%. -This olefinic ketal Claisen reaction is useful for preparing trans-disubst as well as trans-trisubst. olefinic bonds. The above producure is the last of a succession of 3 similar steps. F. e. and catalysts s. W. S. Johnson et al., Am. Soc. 92, 4463 (1970) Proc. Natl. Acad. Sci. U.S. 67, 1462, 1465, 1810, 1824 (1970) geospecific synthesis of ethylene derivs., review, s. J. Reucroft and P. G. Sammes, Quart. Rev. 25,135 (1971). 

Via intermediates Geospecific synthesis of trisubst. ethylene derivs. 

Mercuric bromide cuprous bromide Geospecific synthesis... 

Geospecific synthesis of ethylenecarboxylic acids from 1-vinyllactones... 

Organolithium compds.jiodinejsodium hydroxide Geospecific synthesis of ethylene derivs. from a,p-ethyleneboronic acid esters Inversion of configuration... 

Geospecific synthesis of 2-ethylenealcohols from aldehydes and phosphonium salts... 

Winter s. Corey Wittig synthesis 27, 893 -, cation and anion effects 18,912 suppl. 26 -, geospecific control 18, 912 suppl. 28... 

Geospecific synthesis. A soln. of n-butyllithium in fi-hexane added dropwise at -70 to -65° under Ng to a stirred ethereal soln. of a-methyl-j -bromoisocinnamyl 2-tetrahydropyranyl ether, some tetrahydrofuran added towards the end of the addition, stirring continued 1 hr. at -70°, poured on Dry Ice, and allowed to stand overnight 3-(2-tetrahydropyranyloxymethyl)-2-phenylisocrotonic acid. Y 66%. - Isomerization and lactone formation occurs if the hydroxyl group is not blocked. F. e. s. R. Raap, C. G. Chin, and R. G. Micetich, Can. J. Chem. 49, 2143 (1971). 

Sodium acetate Synthesis of ethylene derivs. from a-silylketones Control of geospecificity by acidic workup s. 32, 865... 

Cuprous iodide n-butyllithium Geospecific synthesis of enesilanes from silylacetylenes... 

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