Synthesis of novel chiral hydrobenzoin mono-tert-butyl ethers derived from m-hydrobenzoin and their application as chiral auxiliaries in the diastereoselective reduction of α-keto esters

1,2-Diphenylethane-1,2-diyl diisonicotinate monohydrate

“…For general background, see: Aspinall et al (2003); Takenaka et al (2006); MacMahon et al (2001); Schuster et al (2005). For related structures, see: Shi et al (2006).…”

“…Synthesis of chiral molecules containing pyridine rings has attracted considerable attention in recent years (Aspinall, et al, 2003;Takenaka, et al, 2006;MacMahon, et al, 2001;Schuster, et al, 2005). In the title compound, (I), C 26 H 20 NO 2 , all bond lengths and angles show normal values (Shi, et al, 2006).…”

Enantioselective Synthesis of (+)-Polyanthellin A via Cyclopropane-Aldehyde (3+2)-Annulation

“…The former only resulted in decomposition, while N-bromosuccinimide gave several major products, with the bromohydrins formed unselectively. To enable epoxidation, the neopentyl iodide was reduced under forcing conditions 56 [LiEt 3 BH, THF-HMPA (4:1), 70°C ] to cleanly afford alkene 66. Epoxidation with dimethyldioxirane 57 provided a 1.7:1.0 mixture of epoxides as the sole products which, after reduction with lithium triethylborohydride, gave 64.…”

Lithium tri-sec-Butylborohydride (l-Selectride): A Powerful and Highly Stereoselective Reducing Reagent

“…It has been used for the diastereoselective reduction of the ketones to give the alcohol, 1-10 selective 1,4-reduction of the enones by conjugate addition of hydride to afford ketones 11,12 or alcohols, 13 conjugate reduction of exocyclic acrylonitrile derivatives, 14 reduction of the double bond 15 and iodide. 16 It was also found to be an efficient reagent for the desymmetrization of mesodiesters, 17 dehalogenation of monohalopyridines, 18 rearrangement of 5-trimethylsilylthebaine, 19 reductive cleavage of exoxides, 20 and deprotection of N-carbomethoxysubstituted opioids to N-noropioids. 21 Lithium tri-sec-butylborohydride is commercially available, but can also be readily prepared by addition of tri- 23 Various enantiomerically pure aziridino ketones can be stereoselectively reduced by L-Selectride to provide the corresponding alcohols with high diastereoselectivities and yields.…”