D diethyl

Phospholipids in purple membrane of Halobacterium Silica gel G halobium Note H = hexane, D = diethyl ether, F = formic acid, BuOH = butanol. 23... 

Although it was also Henbest who reported as early as 1965 the first asymmetric epoxidation by using a chiral peracid, without doubt, one of the methods of enantioselective synthesis most frequently used in the past few years has been the "asymmetric epoxidation" reported in 1980 by K.B. Sharpless [3] which meets almost all the requirements for being an "ideal" reaction. That is to say, complete stereofacial selectivities are achieved under catalytic conditions and working at the multigram scale. The method, which is summarised in Fig. 10.1, involves the titanium (IV)-catalysed epoxidation of allylic alcohols in the presence of tartaric esters as chiral ligands. The reagents for this asyimnetric epoxidation of primary allylic alcohols are L-(+)- or D-(-)-diethyl (DET) or diisopropyl (DIPT) tartrate,27 titanium tetraisopropoxide and water free solutions of fert-butyl hydroperoxide. The natural and unnatural diethyl tartrates, as well as titanium tetraisopropoxide are commercially available, and the required water-free solution of tert-bnty hydroperoxide is easily prepared from the commercially available isooctane solutions. 

L-diethyl tartrate (natural) [A] (-)-D-diethyl tartrate (unnatural) [B]... 

D,D-Diethyl-S-2-diethylaminoethyl phosphorothiolate [78-53-5] M 269.3, m 98-99". from isopropanol/ethyl ether. 

The Intermediate In this synthesis of disparlure, (Z)-2-tridecenol, Is obtained by hydrogenation of 2-trldecynol In the presence of a palladium catalyst poisoned with barium sulfate and quinoline. Oxidation of (Z)-2-tridecenol with tert-butyl hydroperoxlde/tItanium tetralsopropoxlde/D (-)-diethyl tartrate gives (2R, 3S)-epoxytrldecanol In enantiomeric excess reported to be as much as 98 percent after recrystalllzatlon. 

This paper describes the theory which permits us to characterize adequately the stereosequence length in stereoregular polymers from the equilibrium percent crystallinity at room temperature and from the melting points of the polymers. Results based on this theory are given on the characterization of the isotactic stereosequence length in the crystalline fractions of polypropylene oxide polymers made from the following catalyst systems (a) ferric chloride (17, 19) (b) diethyl zinc-water (10) (c) diethyl zinc-water-isopropylamine (d) diethyl zinc-water-cyclohexylamine (14). 

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