98104-30-4Relevant articles and documents
Enantioselective Hydroazidation of Trisubstituted Non-Activated Alkenes
Meyer, Daniel,Renaud, Philippe
supporting information, p. 10858 - 10861 (2017/08/30)
A one-pot procedure for the enantioselective hydroazidation of non-activated trisubstituted alkenes is described. Hydroboration with monoisopinocampheylborane (IpcBH2) provides dialkylboranes that are in situ selectively converted into monoalkyl-substituted catecholboranes; these undergo radical azidation upon treatment with benzenesulfonyl azide and a radical initiator. Enantiomerically enriched azides were thus obtained in yields of 59–81 % and enantioselectivities of up to 94:6 e.r. (98:2 e.r. if the intermediate dialkylborane is purified by crystallization). A rapid access to enantiomerically pure (+)-rodocaine is also described. The use of other arenesulfonyl radical traps enables enantioselective hydroallylation, hydrosulfanylation, and hydrobromination reactions with yields of 71–86 %.
Amber-woody scent: Alcohols with divergent structure present common olfactory characteristics and sharp enantiomer differentiation
Margot, Christian,Simmons, Dana P.,Reichlin, Daniel,Skuy, David
, p. 2662 - 2684 (2007/10/03)
Only one out of the four possible trans isomers of the important perfumery alcohol Norlimbanol (1) possesses a very strong amber-woody smell, the isomer 1A with (1′ R,3S,6'S) absolute configuration. Its enantiomer 1B is almost odorless and devoid of amber-woody character, whereas the diastereoisomers 1C and 1D are considerably weaker and perceptible only by the most-sensitive persons. The same is true for a whole series of perceptual analogs of 1, including β-alkoxy alcohols. These ethers belong to two structural classes: [(2,2,6-trimethylcyclohexyl)oxy]- (see 3, 4, and 16) or {[2-(tert-butyl)cyclohexyl]oxy)alkan-2-ol derivatives (see 19 and 20; Table). A superimposition model allowing for good overlap of the respective hydroxylated side chains offers a tentative explanation for the shared perceptual characteristics of the two classes (Fig. 5). The lipophilic cyclohexane moieties present only a minimal overlap in this model, suggesting that quite larger molecules might possess the same smell. (S)-Configured β-alkoxy alcohols can conveniently be obtained on a larger scale by enantioselective reduction of the corresponding ketones (Scheme 9).
Chiral Sulfur Compounds. Part 25. Diastereoselective 1,2-Additions of Lithiated (+)-(S)-N-tert-Butyldiphenylsilyl-S-methyl-S-phenylsulfoximine to Ketones
Pyne, Stephen G.,Dong, Zemin,Skelton, Brian W.,White, Allan H.
, p. 2607 - 2614 (2007/10/02)
Lithiated (+)-(S)-N-tert-butyldiphenylsilyl-S-methyl-S-phenylsulfoximine 2f reacts with prochiral ketones to give a mixture of diastereomeric β-hydroxy sulfoximine adducts with a diastereoselection ranging from 79:21 to 98:2 depending upon the steric demand of the ketone.Racemic chiral cyclic ketones react with 2f to give a mixture of diastereoisomeric β-hydroxy sulfoximine adducts which could be separated by a combination of column chromatography and recrystallization.Thermolysis of the diastereoisomerically pure adducts gave 2-alkylcyclohexanones in high enantiomeric purity.The relative stereochemistries of four of the β-hydroxy sulfoximine adducts have been unequivocally determined from single-crystal X-ray structural analysis.The stereochemical outcome of these 1,2-additions can best be rationalized by invoking competing boat transition states.
