Ethers reduction

Preparation of 19-norsteroids from 19-substituted steroids by transformations of 6/3, 19-ethers reductive cleavage of 5o -bromo-6/3,19-ethers, 266... 

Jacobsen epoxidation 359 -, Katsuki epoxidation 361 -, Mukaiyama-aldol reaction 367 f. -, oxime ether reduction 363 -, Sharpless asymmetric dihydroxyla-tion 361... 

Cyclohexyl ethyl ether [TMSI-catalyzed ketone-unsymmetrical ether reduction], 124... 

Iodoalkane, oxirane iodoreduction to, cyclohexyl iodide, 136 4-Iodobenzyloxytriethylsilane, ether reduction, 126 Ionic hydrogenation ... 

In the asymmetric reduction of ketones, stereodifferentiation has been explained in terms of the steric recognition of two substituents on the prochiral carbon by chirally modified reducing agents40. Enantiomeric excesses for the reduction of dialkyl ketones, therefore, are low because of the little differences in the bulkiness of the two alkyl groups40. In the reduction of ketoxime ethers, however, the prochiral carbon atom does not play a central role for the stereoselectivity, and dialkyl ketoxime ethers are reduced in the same enantiomeric excess as are aryl alkyl ketoxime ethers. Reduction of the oxime benzyl ethers of (E)- and (Z)-2-octanone with borane in THF and the chiral auxiliary (1 R,2S) 26 gave (S)- and (R)-2-aminooctane in 80 and 79% ee, respectively39. 

---