Enantioselective synthesis of C2-functionalized, N-protected morpholines and orthogonally N,N′-protected piperazines via organocatalysis
摘要:
In this Letter, we describe a novel three-step, one-pot procedure for the enantioselective synthesis of N-benzyl protected morpholines and orthogonally N,N'-protected piperazines with chiral alkyl groups installed at the C2 position of each heterocyclic core via organocatalysis. This methodology allows for the rapid preparation of functionalized morpholines and piperazines that are not readily accessible through any other chemistry in good to excellent % ee (55-98% ee). (C) 2011 Elsevier Ltd. All rights reserved.
Vasicine from Adhatoda vasica as an organocatalyst for metal-free Henry reaction and reductive heterocyclization of o-nitroacylbenzenes
作者:Sushila Sharma、Manoranjan Kumar、Vinod Bhatt、Onkar S. Nayal、Maheshwar S. Thakur、Neeraj Kumar、Bikram Singh、Upendra Sharma
DOI:10.1016/j.tetlet.2016.09.095
日期:2016.11
Vasicine, a quinazolinealkaloid, from the leaves of Adhatodavasica, has been utilized as an efficient catalyst for metal and base free Henry reaction of various aldehydes with nitro alkanes. The method can be used in the synthesis of various β-nitro alcohols under mild reaction conditions without use of hazardous organic solvents and expensive catalysts. Vasicine is also applied successfully for
Precursor Directed Biosynthesis of an Orthogonally Functional Erythromycin Analogue: Selectivity in the Ribosome Macrolide Binding Pocket
作者:Colin J. B. Harvey、Joseph D. Puglisi、Vijay S. Pande、David E. Cane、Chaitan Khosla
DOI:10.1021/ja304682q
日期:2012.7.25
antibiotic activity on the size and degree of unsaturation of the precursor. Based on these leads, we also report the precursor-directed biosynthesis of 15-propargyl erythromycin A, a novel antibiotic that not only is as potent as erythromycin A with respect to its ability to inhibit bacterial growth and cell-free ribosomal protein biosynthesis but also harbors an orthogonal functional group that is capable
大环内酯类抗生素红霉素 A 及其半合成类似物已成为治疗传染病最有用的抗菌剂之一。使用最近开发的用于 6-脱氧红霉素 D 类似物的前体导向生物合成和菌落生物测定的化学遗传策略,我们确定了一类新的炔基和烯基取代的大环内酯类,其活性与天然产物的活性相当。进一步的分析揭示了抗生素活性对前体的大小和不饱和度的显着和出乎意料的依赖性。基于这些线索,我们还报告了 15-炔丙基红霉素 A 的前体导向生物合成,
Supramolecular Catalyst for Aldehyde Hydrogenation and Tandem Hydroformylation-Hydrogenation
The chemoselective reduction of aldehydes and the tandemhydroformylation–hydrogenation of terminal alkenes are possible with a supramolecularcatalyst that operates by a novel mechanism involving substrate activation by hydrogen bonding and subsequent metal–ligand bifunctional hydrogenation (see scheme).
Organocatalytic Addition on 1,2-Bis(sulfone)vinylenes Leading to an Unprecedented Rearrangement
作者:Adrien Quintard、Alexandre Alexakis
DOI:10.1002/chem.200901535
日期:2009.10.26
An unprecedentedrearrangement of 1,2‐bis(sulfone)vinylenes used in aminocatalysis led to the formation of highly useful gem‐disulfones (see scheme). By using aminal–pyrrolidine organocatalysts, the 1,2‐sulfone shift was generalised, leading to highly versatile adducts using both ketones and aldehydes. It represents a valuable alternative for the α‐alkylation of carbonyl compounds.
A new method has been developed for the sequential gem-thioborylation of readily available aldehydes via the cobalt-catalyzed diboration reaction. The N-heterocyclic carbene (NHC)–cobalt complex has been used as a catalyst for the diboration of aldehydes to generate α-oxyl boronic esters, which react with lithium thiolates to form a tetracoordinate boronate species, which undergoes 1,2-metalate rearrangement