118200-96-7Relevant articles and documents
Asymmetric synthesis of α-Tocopherol
Hengartner, Urs,Chougnet, Antoinette,Liu, Kegang,Woggon, Wolf-D.
experimental part, p. 1306 - 1311 (2010/06/12)
α-Tocopherol was synthesized from a chiral intermediate α-hydroxy ester by means of two ring-closing methods to yield the chromanol in 94 % diastereomeric excess.
Studies on the stereoselective synthesis of the marine antitumor agent eleutherobin
Carter, Rich,Hodgetts, Kevin,McKenna, Jeff,Magnus, Philip,Wren, Stephen
, p. 4367 - 4382 (2007/10/03)
(+)-Carvone has been converted into the sulfone 14 which comprises the left-hand side of the cytotoxic sesquiterpene, eleutherobin 1. Julia coupling of 14 to the aldehyde 21, followed by oxidation, dissolving metal reduction and stereoselective reduction
Syntheses, Structures, and Enzymatic Evaluations of Conformationally Constrained, Analogue Inhibitors of Carnitine Acetyltransferase: (2R,6R)-, (2S,6S)-, (2R,6S)-, and (2S,6R)-6-(Carboxylatomethyl)-2-(hydroxymethyl)-2,4,4-trimethylmorpholinium
Sun, Guobin,Savle, Prashant S.,Gandour, Richard D.,a'Bhaird, Noirin Nic,Ramsay, Rona R.,Fronczek, Frank R.
, p. 6688 - 6695 (2007/10/03)
The syntheses and structures of the four stereoisomers of 6-(carboxylatomethyl)-2-(hydroxymethyl)-2,4,4-trimethylmorpholinium, 1, are described.The key step in the synthetic strategy involves an intramolecular Michael addition reaction.Condensation of nonracemic 3-(methylamino)-2-methylpropane-1,2-diol, 3, with methyl 4-bromo-2-butenoate followed by intramolecular Michael addition gives a mixture of two diastereomers of methyl 2-acetate, 5.The diastereomeric ratio of the products in this reaction changes from 6:1 to 1:1 with a change in solvent from diethyl ether:methanol (35:1, v:v) to methanol.The structures and absolute configurations of 1 were determined by single crystal X-ray analyses.In crystals and solution, the morpholinium rings adopt a chair conformation with carboxylatomethyl occupying an equatorial position.All four stereoisomers inhibit pigeon breast carnitine acetyltransferase (CAT).Of this series, (2S,6R)-1 binds to CAT most strongly with a Ki of 190 +/- 20 μM and an IC 50 of 0.42 mM.The enzymatic assays of 1 confirm that CAT recognizes both configurations at C2 and C6 in the analogues.CAT has a different conformation when it binds carnitine or acetylcarnitine than when it binds 1.This latter conformation may resemble that when CAT catalyzes acetyl transfer.
Catalytic Asymmetric Epoxidation and Kinetic Resolution: Modified Procedures Including in Situ Derivatization
Gao, Yun,Hanson, Robert M.,Klunder, Janice M.,Ko, Soo Y.,Masamune, Hiroko,Sharpless, K. Barry
, p. 5765 - 5780 (2007/10/02)
The use of 3A or 4A molecular sieves ( zeoiltes ) substantially increases the scope of the titanium(IV)-catalyzed asymmetric epoxidation of primary allylic alcohols.Whereas without molecular sieves epoxidations employing only 5 to 10 mol percent Ti(O-i-Pr)4 generally led to low conversion or low enantioselectivity, in the presence of molecular sieves such reactions generally led to high conversion (>95percent) and high enantioselectivity (90-95percent ee).The epoxidations of 20 primary allylic alcohols are described.Especially noteworthy are the epoxidations of cinnamyl alcohol, 2-tetradecyl-2-propen-1-ol, allyl alcohol, and crotyl alcohol-compounds which heretofore had been considered difficult substrates for asymmetric epoxidation.In the case of allylic alcohol, the use of cumene hydroperoxide substantially increases both the reaction rate and the conversion, even in the absence of molecular sieves.In general, enantioselectivities are slightly depressed (by 1-5percent ee) relative to reactions employing 50-100 mol percent Ti(O-i-Pr)4.The epoxidation of low molecular weight allylic alcohols is especially facilitated and, in conjuction with in situ derivatization, provides for the synthesis of many epoxy alcohol synthons which were previously difficult to obtain.The kinetic resolution of four secondary allylic alcohols with 10 mol percent Ti(O-i-Pr)4 is also described.The role of molecular sieves in the reaction and the effects of variation in reaction stoichiometry, oxidant, and tartrate are discussed.
