MICs: A short modular synthesis allows the preparation of novel stable heterocycles that feature a lone pair of electrons on a carbon center. The donorproperties of these mesoionic compounds are greater than those of classical N‐heterocycliccarbenes; they are accessible by deprotonation of the corresponding conjugate acids using comparatively mild bases.
Enantioselective total synthesis of callipeltoside A: two approaches to the macrolactone fragment
作者:David A. Evans、Jason D. Burch、Essa Hu、Georg Jaeschke
DOI:10.1016/j.tet.2008.02.001
日期:2008.5
The enantioselectivetotalsynthesis of callipeltoside A is described. Two syntheses of the macrolactone subunit are included: the first relies upon an Ireland-Claisen rearrangement to generate the trisubstituted olefin geometry and the second utilizes an enantioselective vinylogous aldol reaction for this purpose. Enantioselective syntheses of the sugar and chlorocyclopropane side chain fragments
描述了 callipeltoside A 的对映选择性全合成。包括大环内酯亚基的两种合成:第一种依赖于爱尔兰-克莱森重排来产生三取代的烯烃几何结构,第二种利用对映选择性插烯羟醛反应来实现此目的。还公开了糖和氯代环丙烷侧链片段的对映选择性合成。该天然产物的相对和绝对立体化学通过与侧链片段的两种对映异构体的片段偶联来确定。
作者:Anatoliy P. Marchenko、Heorgiy N. Koidan、Anastasiia N. Hurieva、Igor I. Pervak、Svitlana V. Shishkina、Oleg V. Shishkin、Aleksandr N. Kostyuk
DOI:10.1002/ejoc.201200282
日期:2012.7
Three original approaches to the synthesis of N-alkyl-N′-phosphanylbenzimidazolium salts, which are precursors of the corresponding carbenes, were developed. New stableN-alkyl-N′-phosphanylbenzimidazol-2-ylidenes were prepared in good yields. X-ray analysis of a carbene was made and the chemical properties of the carbenes were studied. The reactions with O-, N-, and C-nucleophiles were found to proceed
on the 2,4-diaminotriazine scaffold are described. These complexes are active catalysts for the Suzuki–Miyaura cross-coupling of a wide range of aryl, heteroaryl (including benzoxazole, thiazole, pyridine, pyrimidine, thiazole), primary and secondary alkyl halides, and pseudohalides with different organoboronate reagentsgiving excellent to good isolated yields. Neutral deprotonated complexes seem
Highly Enantioselective Synthesis of Rigid, Quaternary 1,4-Benzodiazepine-2,5-diones Derived from Proline
作者:Stephanie MacQuarrie-Hunter、Paul R. Carlier
DOI:10.1021/ol052182d
日期:2005.11.1
4-benzodiazepine-2,5-diones are extremely useful scaffolds in medicinal chemistry. In this paper, we describe a protocol for retentive C3 alkylation of these materials, thus accomplishing the direct synthesis of enantiopure quaternary 1,4-benzodiazepine-2,5-diones. The high enantioselectivities (up to 99.5%) are attributed to memory of chirality.