Crotyl fluoride

Coumalic acid, 56, 51 Crotyl fluoride, 57,73 18-CROWN-6,57, 30 Curtius rearrangement, 59, 1 Cyanide ion, as catalyst for conjugate addition of aldehydes, 59, 56 p-Cyanobenzenesulfonyl cyanide, 57, 89 2-( 1 -Cyanocyclohexyljhydrazinecarboxylic acid methyl ester, 58,102 Cy a noferrocene, 56, 30 Cyanogen chloride, 57, 88... 

Some alcohols that have been converted into the corresponding fluorides by reactions with diethyldminosulfur trifluoride include 1-octanol, 2-methyl-2-butanol, isobutyl alcohol, cyclooctanol, ethylene glycol, crotyl alcohol, 2-phenylethanol, 2-bromoethanol, ethyl lactate, and ethyl a-hydrox3maphthaleneacetate. ... 

Following the reactions in Scheme 4, the olefin 13 would have to be generated before the formation of the 7r-crotyl species 2. Because the amount of the catalyst present is usually small as compared to the amount of product formed (1000 moles of product/mole catalyst), the quantity of 13 produced will not be significant and should be readily separable from the desired product. In the special case when crotyl chloride is used as the activator, hexadiene can be produced during the very first cycle of reaction, i.e., 13 = 1,4-hexadiene. Among the organic halides, the chloride derivatives are the most effective activators. Bromides are somewhat effective, while fluorides and iodide are rather ineffective (77). 

Andreev and co-workers have undertaken extensive studies on the reactions of allyl, crotyl, and propargyl alcohols with 2-substituted pentafluoropropenes 14.11 Allyl and crotyl alcohol react at 5-20 C with various 2-substituted pentafluoropropenes 14 in the presence of potassium fluoride in dimethylformamide to give -substituted a-(trifluoromethyl) esters 16. Saponification yields the corresponding acids. 

In the presence of a Lewis acid or fluoride ion, imines react with allylsilane to yield the homoallylic amines with high stereoselectivity119,120. Thus, treatment of N-galactosylaldimine 81 with allylsilane in the presence of excess of SnCU yields the corresponding allylated product 82 (equation 54). It is noted that aliphatic aldimines do not react under these conditions. Fluoride ion promoted crotylation of aldimines proceeds in a regiospecific and diasteroselective manner121. A pentacoordinate silicate moiety is involved in this reaction. 

Recently, we have estabhshed the satisfactory method of synthesis of each isomer of crotyl-trifluorosilanes with rather convenient procedure together with the stereochemistry of the reaction with various aldehydes in the presence of fluoride ions. The crotyltrifluorosi-lanes are configurationally very stable and storable for a couple of months at 0 °C without any change of the purity as expected from the low tendency to the metallotropic rearrangement. The present reagent system would thus fulfill almost all conditions for stereoselective crotylation, while chiral modification should be the next target. 

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