Alcohols cyclopropanations, cyclohexane

Chiral Alcohols and Lactones. HLAT) has been widely used for stereoselective oxidations of a variety of prochiral diols to lactones on a preparative scale. In most cases pro-(3) hydroxyl is oxidized irrespective of the substituents. The method is apphcable among others to tit-1,2-bis(hydroxymethyl) derivatives of cyclopropane, cyclobutane, cyclohexane, and cyclohexene. Resulting y-lactones are isolated in 68—90% yields and of 100% (164,165). 

When the reaction of DMFL with alcohols, cyclohexane, or a-methylstyrene is initiated by triplet senitization, the outcome is virtually the same as it is for the direct irradiation. Thus ethers are formed in high yield with the alcohols, direct insertion accounts for the major product in cyclohexane, and the olefin cyclopropanation is stereospecific. 

The A, A -bis(arenesulfonyl)cyclohexane-1,2-diamines used as chiral controllers (see also Houben-Weyl, Vol. E21, pp 1327, 3895) can also be employed as their aluminum complexes to catalyze the cyclopropanation of allylic alcohols with diethylzinc and diiodomethane. ° The bis(sulfonamide)aluminum complex was first prepared in situ in 1,2-dichloroethane and after removal of the solvent in vacuo, cyclopropanation was carried out in dichloromethane at — 20 °C. The enantioselectivities are similar to those obtained with the chiral zinc catalyst described above. However, the most characteristic feature of the chiral aluminum complex catalyzed reaction is that no decrease in the enantioselectivity was observed even at a higher concentration. An electron-withdrawing group on the benzene ring of the sulfonamide or the... 

The effect of solvent was also studied and complexing solvents such as THF or Et20 inhibited the cyclopropanation reaction. Furthermore, the presence of an unprotected allylic alcohol was found to be essential, since the methyl or benzyl ether derived from cinnamyl alcohol afforded almost racemic cyclopropanes. This method has also been extended to the enantioselective cyclopropanation of vinylsilanes and -stannanes (Scheme 4) [13]. The corresponding optically active silyl- and stannyl-substituted cyclopropyhnethanols were obtained in the presence of the chiral N,iV-bis(p-nitrobenzenesulfonyl)-l,2-cyclohexane-diamine 9. 

Scheme 6.28. Asymmetric cyclopropanation of allylic alcohols (a) Using a glucose-derived auxiliary [106] (b) A cyclohexane diol auxiliary [107].

Systematic transmission spectroscopic studies of the transformations were carried out on the systems allene, propene, cyclopropane, zsopropanol and acetone over NaM,HM and NaHM [113-117], 1-butene over NaHY [117,118], allene, propene and cyclopropane over NaHY and NaHZSM-5 [116,117,119-122],neopentane over NaY, NaHY,NaHM and NaHZSM-5 [119,123,124],cyclohexene over HZSM -5 [ 119], 1 -hexene, cyclohexane, cyclohexene, cyclohexadiene and benzene over NaHY and NaHZSM-5 [117,125], allyl alcohol, acrolein and allene over HZSM-5 [ 126], allene and propyne over nonacidic zeohtes NaA, CoNaA, CoNaX, NaY and NaHY [121] and benzene, toluene, ethylbenzene, and cumene over HZSM-5 [127]. 

This reaction was first reported by Perkin in 1883. It is the nucleophilic alkylation between malonic ester and Q, o)-alkyl dihalide to form cyclic aliphatic 1,1-diester or acid and is known as the Perkin reaction or Perkin synthesis. Although it was once referred to as the Perkin condensation, this name should not be used for this type of reaction. Using this protocol, Perkin successfully prepared cyclopropane-, cyclobutane-, cyclopentane-, cyclohexane-, and cycloheptane-1,1-dicarboxylie acids. However, this reaction is often complicated by the side reaction that forms Q, o, a ,a -tetracarboxylic ester from the Sn2 reaction between malonic ester and o, a -alkyl dihalide, this side reaction can be depressed if alcoholic sodium malonic ester is added slowly to the o, a -alkyl dihalide with vigorous stirring. It is interesting that the K2CO3 promoted a reaction between dimethyl 1,3-acetonedicarboxylate and tran5 -l,4-dibromobutene yields vinyldihydrofuran. ... 

The condensed phase can be an aqueous solution [1,2], or liquid saturated hydrocarbons (CsHq [3, 4], C5H12 [5], cyclopropane [6], cyclohexane [7]), or liquid olefins [8] and acetylenes [9], as well as alcohols [10] and liquid ammonia [11 to 14] at various temperatures. Most often, however, a low-temperature inert gas matrix is the condensed phase in which isolated NH radicals are produced [15 to 30]. Also NH adsorbed on zeolite [31] has to be mentioned in this context. 

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