5‘-Substituted-6-carboxylic-2,2‘-bipyridine Acid: A Pivotal Architecton for Building Preorganized Ligands
摘要:
A set of ligands bearing 6-bromo-2,2'-bipyridine pendant arms attached in the 5'-position are described. Trans formation of the bromo to an ester was performed by a carboethoxylation reaction promoted by low-valent Pd(0), while saponification followed by acidification gave the acids. The introduction of an appended function 3-nitrobenzyl, benzamidomethyl, and tert-butylacetyl opens the way to further functionalize these scaffolds for potential labeling of biological material. The synthetic protocols represent a valuable approach to the rational design of ligands bearing oxophilic and anionic sidearms.
DDQ mediated regiospecific protection of primary alcohol and deprotection under neutral conditions: Application of new p -methoxy benzyl-pixyl ether as reagent of choice for nucleoside protection
作者:Penjarla Srishylam、A. Raji Reddy、Shyamapada Banerjee、Santhosh Penta、Yogesh S. Sanghvi
DOI:10.1016/j.tetlet.2017.05.066
日期:2017.6
A simple and efficient protocol is described for regiosepecific protection of primary hydroxyl group both in nucleosides and other molecules with p-methoxy-benzyl 2,7-dimethyl pixylether (MBDPE) in presence of 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Furthermore, swift deprotection of 2, 7-dimethylpixyl (DMPx) is accomplished with DDQ in MeOH. Both procedures are successfully implemented on
一个简单的,高效的协议被用于在两个核苷和其它分子与伯羟基的保护regiosepecific描述p -米乙氧基b enzyl 2,7- d imethyl p ixyl ë疗法(MBDPE)中的存在2,3-二氯5,6-二氰基-1,4-苯醌(DDQ)。此外,用DDQ在MeOH中快速脱保护2,7-二甲基pixyl(DMPx)。两种方法均在革兰氏级合成修饰核苷上成功实现。该方案为DMPx基团的选择性保护和脱保护提供了温和和中性的条件,同时可与其他常规保护基团(例如苯甲酰基,苄基,THP,TBDPS和丙酮化物)相容。
Copper(II)nitrate catalyzed regioselective protection of primary alcohols with 4,4′-dimethoxytrityl and 2,7-dimethyl-9-phenyl xanthen-9-yl groups in nucleosides and carbohydrates
作者:Srishylam Penjarla、S. Rajendra Prasad、Dhande Sudhakar Reddy、Shyamapada Banerjee、Santhosh Penta、Yogesh S. Sanghvi
DOI:10.1080/15257770.2018.1460480
日期:2018.4.3
ABSTRACT Regioselective protection of primary hydroxylgroup in nucleoside and carbohydrate analogs was accomplished using dimethoxytrityl alcohol (DMTr-OH) or dimethylpixyl alcohol (DMPx-OH) in presence of copper(II)nitrate as a Lewis acid catalyst. Excellent selectivity was observed for the protection of primary hydroxylgroup over secondary while glycosidic bond remain unaffected. Utility of this
phosphono-modified backbone mimics based on achiral and chiral N-(dihydroxypropyl)glycine units were obtained by sequential addition of phosphonate and nucleobase moieties to suitably protected dihydroxypropylamines. Simplesyntheticstrategies enabled the preparation of various target derivatives that will be useful as building blocks for the preparation of new synthetic polymers containing a phosphonate
Lewis Acid-Catalyzed Addition of Benzophenone Imine to Epoxides Enables the Selective Synthesis and Derivatization of Primary 1,2-Amino Alcohols
作者:John Jin Lim、David C. Leitch
DOI:10.1021/acs.oprd.8b00133
日期:2018.5.18
Benzophenone imine was found to be an effective ammonia surrogate for the selective preparation of primary 1,2-amino alcohols fromepoxides, including enantiopure epichlorohydrin, in the presence of catalytic Y(OTf)3. High-throughput screening of 48 Lewis acids quickly identified Y(OTf)3 as an effective mediator of the addition reaction under mild conditions. Following acidic hydrolysis, the primary
Novel ethylene glycol compounds bearing various functional groups are used to prepare oligomeric structures. The ethylene glycol monomers can be joined via standard phosphate linkages including phosphorothioate, phosphodiester, and phosphoramidate linkages. Useful functional groups include nucleobases as well as polar groups, hydrophobic groups, ionic groups, aromatic groups and/or groups that participate in hydrogen-bonding.