Synthesis of a Cyclopentane Amide DNA Analogue and Its Base Pairing Properties
摘要:
cpa-DNA monomers containing the bases adenine and thymine have been synthesized starting from the known compound 1 in 12 steps. Partially and fully modified cpa-thymidine and cpa-adenosine containing oligodcoxynucleotides were synthesized by standard oligonucleotide chemistry. Fully modified homo-cpa-A sequences lead to duplex destabilization by -1.4degreesC/mod. relative to DNA. As its congener bca-DNA, cpa-DNA prefers left-handed duplex formation where possible.
A Ru carbene (8, Scheme 2) that contains an internal metal-oxygen chelate is an active metathesis catalyst and is readily obtained by the sequential treatment of Cl2Ru(PPh3)(3) with (2-isopropoxyphenyl)-diazomethane and PCy3. This Ru-carbene complex offers excellent stability to air and moisture and can be recycled in high yield by silica gel column chromatography. The structures of this and related complexes have been unambiguously established by NMR and single-crystal X-ray diffraction studies.
copper-catalyzed coupling reaction of 2-pyridinesulfonates with Grignardreagents revealed that reactions with catalytic Cu(OTf)2 were completed in <40 min. The results differed from those of the previous CuI-catalyzed reactions of tosylates in the presence of additives (LiOMe and TMEDA) for 12–24 h. It was shown that the preferred coordination of the leaving group to the reagents accelerated the reaction
Oxidation of Olefins into α-Phenylseleno Carbonyl Compounds. Highly Regioselective<i>anti</i>-Markownikoff Type Oxidation of Allylic Alcohol Derivatives
作者:Makoto Shimizu、Ryo Takeda、Isao Kuwajima
DOI:10.1246/bcsj.54.3510
日期:1981.11
(C6H5Se)2–(C6H5SeO)2O system, oxoselenenylation reactions of C=C bonds have been examined with allylic and homoallylic alcohol derivatives, and substituted cyclohexenes, and allyl t-butyldimethylsilyl ethers are found to undergo regioselective conversion into β-siloxy α-phenylseleno carbonylcompounds in high yields.
Diastereoselective epoxidation of allylically substituted alkenes using metalloporphyrin catalysts
申请人:Che Chi-Ming
公开号:US20050209470A1
公开(公告)日:2005-09-22
Diastereoselective epoxidation of allylically substituted alkenes using metalloporphyrins as catalyst provides high trans-selectivities (i.e., trans-:cis-epoxide ratio). A diversity of cycloalkenes bearing different allylic substituents are shown to be efficiently epoxidized to afford the corresponding trans-epoxides with excellent trans-selectivities (up to >98%) and good yields (up to 99%). Acyclic allylic alkenes bearing different allylic substituents are efficiently epoxidized to afford the corresponding erythro-epoxides with good erythro-selectivities. The metalloporphyrin-catalyzed reactions exhibit up to 20 times higher trans-selectivities than the conventional method using m-chloroperoxybenzoic acid as oxidant.
Highly Diastereoselective Epoxidation of Allyl-Substituted Cycloalkenes Catalyzed by Metalloporphyrins
作者:Wing-Kei Chan、Peng Liu、Wing-Yiu Yu、Man-Kin Wong、Chi-Ming Che
DOI:10.1021/ol0496475
日期:2004.5.1
Highly diastereoselectiveepoxidations of allyl-substituted cycloalkenes including allylic alcohols, esters, and amines using sterically bulky metalloporphyrins [Mn(TDCPP)Cl] (1) and [Ru(TDCPP)CO] (2) as catalysts have been achieved. The "1 + H(2)O(2)" and "2 + 2,6-Cl(2)pyNO" protocols afforded trans-epoxides selectively in good yields (up to 99%) with up to >99:1 trans-selectivity.
Diastereoselective Diboration of Cyclic Alkenes: Application to the Synthesis of Aristeromycin
作者:Alex J. Vendola、Christophe Allais、Anne-Marie R. Dechert-Schmitt、James T. Lee、Robert A. Singer、James P. Morken
DOI:10.1021/acs.orglett.1c00353
日期:2021.4.16
The Pt-catalyzed diboration of cyclic alkenes is extended to unsaturated heterocycles and bicyclic compounds and can be accomplished in a diastereoselective fashion. The optimal procedures, substrate scope, and diastereoselectivity were investigated, and examples employing both homogeneous and heterogeneous catalysis were examined. Lastly, application to the construction of the nucleoside analog (±)-aristeromycin