نتایج جستجو برای: stereoselective
تعداد نتایج: 4707 فیلتر نتایج به سال:
The synthesis of small rings by functionalization of C(sp(3) )-H bonds remains a great challenge. We report for the first time a copper-catalyzed [1+1+1] cyclotrimerization of acetophenone derivatives under mild reaction conditions. The reaction has a broad scope for the stereoselective synthesis of cyclopropanes by trimerization of acetophenone. The developed transformation is based on an extr...
An unprecedented, highly stereoselective rearrangement of guaianolides, bearing a double bond at the C-6/C-6a position, to tricyclic δ-valerolactones is described.
A highly stereoselective desymmetrization reaction of δ,δ-diaryl-α-diazo-β-ketoesters catalyzed by chiral dirhodium carboxylates forms aromatic cycloaddition products in up to 97% ee.
Unsaturated epsilon-lactones bearing an alpha-arylsulfonyl or alpha-arylsulfoximinyl substituent undergo stereoselective transannular, decarboxylative Claisen rearrangement to give substituted vinylcyclopropanes.
The metallophthalocyanine complex Cr(TBPC)OTf works as a highly efficient, recyclable Lewis acid catalyst for the regio- and stereoselective rearrangements of epoxides to aldehydes.
The vinylogous Mukaiyama aldol reaction (VMAR) allows efficient access to larger segments for complex natural product synthesis, primarily polyketides, through the construction of vicinal hydroxyl and methyl groups as well as di and tri-substituted double bonds in one single operation. In this review, we will highlight stereoselective protocols that have been used in natural product synthesis a...
Regioand stereoselective photoallylation of electron-deficient alkenes by use of allylic silanes via photoinduced electron transfer has been described. Similar photoinduced functionalization reactions such as arylmethylation, alkylation, and silylation can be achieved by using a variety of organosilicon compounds. These photoreactions proceed via radical cations of organosilicon compounds and r...
Chiral guests display kinetic stereoselective threading through chiral porphyrin cages if their chirality is located at the chain ends and not in centers, supporting previously reported entron effect of threading.
A highly stereoselective, efficient and facile route was achieved for the synthesis of novel biochemically potent sugar fused pyrano[3,2- c ]pyranone derivatives starting from inexpensive, naturally occurring d -galactose -glucose.
A stereoselective route towards protoilludanoids from simple aromatic precursor is described. The methodology involves in situ generation of spiroepoxycyclohexadienone and cycloaddition with cyclopentadiene and photochemical 1,3-acyl shift.
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