A practical, general and efficient protocol for the catalytic epoxidation of alkenes has been developed. The in situ generation of reactive dioxiranes capable of epoxidizing a variety of alkenes under biphasic conditions has been accomplished using phase transfer catalysts bearing a carbonyl group. Optimal epoxidation conditions employ 10 mol % of 1-dodecyl-1-methyl-4-oxopiperidinium triflate (8d(+)OTf(-)) in a CH2Cl2/pH 7.5-8.0 biphase using potassium monoperoxosulfate (Oxone) as the oxidant. Optimization of the conditions identified (1) slow addition rate, (2) pH 7.5-8.0, (3) N-dodecyl chain, and (4) the triflate salt as key experimental and structural variables. A selection of nine olefins was successfully oxidized to the corresponding epoxides in 83-96% yield.
Catalytic, stereospecific syn-dichlorination of alkenes
作者:Alexander J. Cresswell、Stanley T.-C. Eey、Scott E. Denmark
DOI:10.1038/nchem.2141
日期:2015.2
As some of the oldest organic chemical reactions known, the ionic additions of elemental halogens such as bromine and chlorine to alkenes are prototypical examples of stereospecific reactions, typically delivering vicinal dihalides resulting from anti-addition. Although the invention of enantioselective variants is an ongoing challenge, the ability to overturn the intrinsic anti-diastereospecificity
Total Synthesis and Biological Evaluation of Siladenoserinol A and its Analogues
作者:Masahito Yoshida、Koya Saito、Hikaru Kato、Sachiko Tsukamoto、Takayuki Doi
DOI:10.1002/anie.201801659
日期:2018.4.23
followed by regioselective sulfamate formation of the serinol moiety afforded the desired siladenoserinol A, and benzoyl and desulfamated analogues were also successfully synthesized. Biologicalevaluation showed that the sulfamate is essential for biological activity, and modification of the acyl group on the bicycloketal can improve the inhibitory activity against the p53–Hdm2 interaction.
We have developed a new protocol for making aldol adducts in a one-pot reaction between esters and silyl enol ethers in the presence of DIBALH without isolating the intermediate aldehydes. Lewis acid activation of the initially formed aluminated hemiacetals produces highly reactive electrophilic aldehyde equivalents in situ. Using this protocol, various aldol adducts can be readily obtained in up to 90% yield on a large scale.
Rhodium catalyzed hydroacylation of ethylene with 4-pentenals. reactions of 4-hexenal-1-d
作者:Krishnakant P. Vora、Charles F. Lochow、Roy G. Miller
DOI:10.1016/s0022-328x(00)94430-9
日期:1980.6
A catalyst derived from 2,4-pentanedionatobis(ethylene)rhodium(I), I, promoted the addition of 4-pentenal to ethylene. The reaction was accompanied by the formation of double bond migration products derived from the 4-pentenal reactant and from the 6-hepten-3-one primary product. Compound I accomplished the addition of 4-hexenal to ethylene to afford high yields of 6-octen-3-one. The fate of the aldehyde