Preparation of enantiomerically enriched compound using enzymes. Part 3. Enzymic preparation of enantiomerically enriched tertiary .alpha.-benzyloxy acid esters. Application to the synthesis of (S)-(-)-frontalin
The synthesis and antibacterial activity of two new highly truncated derivatives of the natural product abyssomicin C are reported. This work outlines the limits of structural truncation of the natural product and consequently provides insights for further structure–activity relationship studies towards novel antibiotics targeting 4-amino-4-deoxychorismate (ADC) synthase. Specifically, it is demonstrated
Grignard-type allylation of carbonyl compounds in methanol by the electrochemically recycled allyltin reagent.
作者:Kenji Uneyama、Hiroyuki Matsuda、Sigeru Torii
DOI:10.1016/s0040-4039(01)81748-2
日期:——
An electrochemical allylation of aldehydes and ketones in methanol was achieved by the electroreductive regeneration of diallyltin reagent in the presence of a catalytic amount of tin, affording the corresponding homoallyl alcohols in 72 – 91% yields.
Ruthenium-Catalyzed Alder Ene Type Reactions. A Formal Synthesis of Alternaric Acid
作者:Barry M. Trost、Gary D. Probst、Andreas Schoop
DOI:10.1021/ja981540n
日期:1998.9.1
by involving Pd-catalyzed cross-coupling and asymmetric dihydroxylation. The ruthenium-catalyzed coupling proceeds best in the absence of alcohol protecting groups to maximize regioselectivity. The examples of this addition illustrated herein help elucidate some of the important factors controlling regioselectivity. They also illustrate the excellent chemoselectivity. T...
Ring-Closing Metathesis of Allylic O,O- and N,O-Acetals
作者:Sape S. Kinderman、Robin Doodeman、Jetze W. van Beijma、Jaap C. Russcher、Kim C. M. F. Tjen、T. Martijn Kooistra、Homayun Mohaselzadeh、Jan H. van Maarseveen、Henk Hiemstra、Hans E. Schoemaker、Floris P. J. T. Rutjes
A variety of allylic O,O -a ndN,O-acetals were synthesized using a mild palladium-catalyzed coupling of an alcohol or sulfonamide with an alkyl or aryl 1,2-propadienyl ether. The resulting linear acetals were used for the synthesis of unsaturated ringsvia ring-closing metathesis, in which the acetal carbon ± a precursor for oxycarbenium or N-sulfonyliminium ions, respectively ± served as a reactive
使用醇或磺酰胺与烷基或芳基 1,2-丙二烯基醚的温和钯催化偶联合成了各种烯丙基 O,O -a ndN,O-缩醛。所得线性缩醛用于通过闭环复分解合成不饱和环,其中缩醛碳±氧碳鎓或 N-磺酰亚胺鎓离子的前体分别±充当进一步引入官能团的反应中心。产物——不饱和氧和氮杂环支架——为衍生提供了多种机会,如取代二氢吡喃、色烯、对映体纯四氢吡啶和对映体纯的喹啉氨基酸的合成所示。
Asymmetric addition of allyltrimethylsilane to (–)-menthyl pyruvate and phenylglyoxylate
作者:Iwao Ojima、Yuji Miyazawa、Miyoko Kumagai
DOI:10.1039/c39760000927
日期:——
The reaction of allyltrimethylsilane with α-keto esters in the presence of titanium tetrachloride afforded a γδ-unsaturated α-hydroxyvalerate in high yield, which with chiral α-keto esters in asymmetric synthesis gave 16–55% enantiomeric excess product.