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Janakiram Vaitla Yannick T. Boni Huw M. L. Davies 《Angewandte Chemie (International ed. in English)》2020,59(19):7397-7402
Regio‐ and stereoselective distal allylic/benzylic C?H functionalization of allyl and benzyl silyl ethers was achieved using rhodium(II) carbenes derived from N‐sulfonyltriazoles and aryldiazoacetates as carbene precursors. The bulky rhodium carbenes led to highly site‐selective functionalization of less activated allylic and benzylic C?H bonds even in the presence of electronically preferred C?H bonds located α to oxygen. The dirhodium catalyst Rh2(S‐NTTL)4 is the most effective chiral catalyst for triazole‐derived carbene transformations, whereas Rh2(S‐TPPTTL)4 works best for carbenes derived from aryldiazoacetates. The reactions afford a variety of δ‐functionalized allyl silyl ethers with high diastereo‐ and enantioselectivity. The utility of the present method was demonstrated by its application to the synthesis of a 3,4‐disubstituted l ‐proline scaffold. 相似文献
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Yadav JS Boyapelly K Alugubelli SR Pabbaraja S Vangala JR Kalivendi SV 《The Journal of organic chemistry》2011,76(8):2568-2576
The first total synthesis of recently isolated diacetylene alcohols oploxyne A, oploxyne B, and their C-10 epimers was accomplished. The structure of natural oploxyne B has been revised. The key steps involved are base-induced double elimination of a carbohydrate-derived β-alkoxy chloride to generate the chiral acetylenic alcohol and Cadiot-Chodkiewicz cross-coupling reaction. The target compounds displayed potent cytotoxicity against neuroblastoma and prostate cancer cell lines. 相似文献
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Dr. Janakiram Vaitla Yannick T. Boni Prof. Dr. Huw M. L. Davies 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(19):7467-7472
Regio- and stereoselective distal allylic/benzylic C−H functionalization of allyl and benzyl silyl ethers was achieved using rhodium(II) carbenes derived from N-sulfonyltriazoles and aryldiazoacetates as carbene precursors. The bulky rhodium carbenes led to highly site-selective functionalization of less activated allylic and benzylic C−H bonds even in the presence of electronically preferred C−H bonds located α to oxygen. The dirhodium catalyst Rh2(S-NTTL)4 is the most effective chiral catalyst for triazole-derived carbene transformations, whereas Rh2(S-TPPTTL)4 works best for carbenes derived from aryldiazoacetates. The reactions afford a variety of δ-functionalized allyl silyl ethers with high diastereo- and enantioselectivity. The utility of the present method was demonstrated by its application to the synthesis of a 3,4-disubstituted l -proline scaffold. 相似文献
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Aza‐Quaternary Scaffolds from Selective Bond Cleavage of Bridgehead‐Substituted 7‐Azabicyclo[2.2.1]heptane: Total Synthesis of (+)‐Cylindricines C–E and (−)‐Lepadiformine A
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Prof. Dr. Ganesh Pandey Vaitla Janakiram 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(37):13120-13126
A novel bridgehead‐substituted aza‐bicyclic framework has been designed and developed in both enantiomeric forms through an asymmetric desymmetrization reaction. Strategic exploitation of the ring strain in the aza‐bicyclic framework has been utilized for the construction of the chiral aza‐quaterenary scaffolds by selective bond fragmentation processes. Furthermore, a strategically designed precursor is employed for selective bond cleavage to initiate a cascade rearrangement for the total synthesis of the 1‐azaspirotricyclic marine alkaloids (+)‐cylindricines C, D, and E, as well as (?)‐lepadiformine A. An oxidation/retro‐aldol/aza‐Michael sequence generated three new chiral centers with the required configuration in one pot. 相似文献
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