排序方式: 共有46条查询结果,搜索用时 312 毫秒
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Benohoud M Tuokko S Pihko PM 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(30):8404-8413
A highly versatile and efficient hydrosilylation method by palladium nanoparticle catalysis allows the direct and chemoselective synthesis of 1) enolsilanes of high isomeric purity, 2) saturated aldehydes or ketones, or 3) the corresponding saturated acetals from α,β-unsaturated aldehydes or ketones. The choice of the product is determined by simply switching the solvent from THF to mixtures of THF/water or THF/alcohol. 相似文献
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A Catalyst Designed for the Enantioselective Construction of Methyl‐ and Alkyl‐Substituted Tertiary Stereocenters
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Dr. Aurélie Claraz Dr. Gokarneswar Sahoo Dénes Berta Dr. Ádám Madarász Dr. Imre Pápai Prof. Dr. Petri M. Pihko 《Angewandte Chemie (International ed. in English)》2016,55(2):669-673
Tertiary methyl‐substituted stereocenters are present in numerous biologically active natural products. Reported herein is a catalytic enantioselective method for accessing these chiral building blocks using the Mukaiyama–Michael reaction between silyl ketene thioacetals and acrolein. To enable remote enantioface control on the nucleophile, a new iminium catalyst, optimized by three‐parameter tuning and by identifying substituent effects on enantioselectivity, was designed. The catalytic process allows rapid access to chiral thioesters, amides, aldehydes, and ketones bearing an α‐methyl stereocenter with excellent enantioselectivities, and allowed rapid access to the C4–C13 segment of (?)‐bistramide A. DFT calculations rationalized the observed sense and level of enantioselectivity. 相似文献
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A highly stereocontrolled and efficient synthesis for a fully functionalized C 10-C 22 fragment of pectenotoxin 2 is described using a convergent sequence involving a stereoselective methylation of beta-hydroxyketone as a key step. 相似文献
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Minna Kortelainen Aku Suhonen Dr. Andrea Hamza Dr. Imre Pápai Dr. Elisa Nauha Dr. Sanna Yliniemelä‐Sipari Prof. Dr. Maija Nissinen Prof. Dr. Petri M. Pihko 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(26):9493-9504
A series of small, unsymmetrical pyridine‐2,6‐dicarboxylamide oligoamide foldamers with varying lengths and substituents at the end groups were synthetized to study their conformational properties and folding patterns. The @‐type folding pattern resembled the oxyanion‐hole motifs of enzymes, but several alternative folding patterns could also be characterized. Computational studies revealed several alternative conformers of nearly equal stability. These folding patterns differed from each other in their intramolecular hydrogen‐bonding patterns and aryl–aryl interactions. In the solid state, the foldamers adopted either the globular @‐type fold or the more extended S‐type conformers, which were very similar to those foldamers obtained computationally. In some cases, the same foldamer molecule could even crystallize into two different folding patterns, thus confirming that the different folding patterns are very close in energy in spite of their completely different shapes. Finally, the best match for the observed NOE interactions in the liquid state was a conformation that matched the computationally characterized helix‐type fold. 相似文献
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