Gold-Catalyzed Stereocontrolled Synthesis of 2,3-Bis(acetoxy)-1,3-dienes
作者:Xiaogen Huang、Teresa de Haro、Cristina Nevado
DOI:10.1002/chem.200900391
日期:2009.6.8
the stereochemistry: 2,3‐Bis(acetoxy)‐1,3‐dienes are obtained in a stereocontrolled manner by a novel tandem 1,2‐/1,2‐bis(acetoxy) rearrangement (see scheme, R1 and R2 are δ+ stabilizing). Upon stabilization of the reaction intermediates, the ligand attached to gold controls the stereochemistry of the alkene in the second acetate migration, that is, N‐heterocyclic carbenes (NHC) favor cis alkenes, whereas
改变配体,改变立体化学:通过新的串联1,2- / 1,2-双(乙酰氧基)重排以立体控制方式获得2,3-双(乙酰氧基)-1,3-二烯(参见方案, R 1和R 2为δ +稳定化。反应中间体稳定后,与金连接的配体控制了第二次乙酸盐迁移过程中烯烃的立体化学,即N-杂环卡宾(NHC)有利于顺式烯烃,而膦配体则选择性地提供了反式烯烃。
Enzymatic kinetic resolution of internal propargylic diols. Part I: a new approach for the synthesis of (S)-pent-2-yn-1,4-diol, a natural product from Clitocybe catinus
作者:Jeiely G. Ferreira、Cleverson R. Princival、Dyego M. Oliveira、Renata X. Nascimento、Jefferson L. Princival
DOI:10.1039/c5ob00386e
日期:——
Employing a two round sequence EKR, mono- and bis-acetoxy propargylic products were obtained in a high enantiomeric ratio (E > 200). The efficiently resolved chiral 8b was applied in a concise synthesis of (S)-1b, an optically active natural product produced by fungi Clitocybe catinus.
CeCl3-mediated addition of acetylenic bis-lithium salts to aldehydes and ketones: An efficient route to bis-substituted alkyne diols
作者:Jefferson Luiz Princival、Jeiely Gomes Ferreira
DOI:10.1016/j.tetlet.2017.07.094
日期:2017.9
An efficient, chemoselective protocol to access propargylic diols via a CeCl3-mediated addition reaction is reported. Propargylic alcohols were transformed into the corresponding acetylenic bis-lithium salt intermediates, which react with aldehydes and ketones in the presence of dry CeCl3 to furnish the corresponding bis-substituted alkyne diols. This protocol does not involve protection-deprotection
A library of star-shaped 2H-imidazolines has been synthesized via Debus Radziszewski condensation from 1,2-diketones and ketone starting materials. Selective reduction of one imine group of the 2H-imidazole intermediate with LiAlH4 or catalytic flow hydrogenation furnished 2H-imidazolines, which could be conveniently diversified by reacting the amine N with electrophiles, resulting in a set of 21 amide-, carbamate-, urea-, and allylamine-containing products. In total, five points of diversification could be used, which allow the production of a set of functionally diverse compounds. The synthesis of acylated 2H-imidazolidines resulted in intrinsically labile compounds, which spontaneously degraded to acyclic derivatives, as shown for the reaction of 2H-imidazolidine with hexylisocyanate.
Mikhailovskii,D.I. et al., Journal of Organic Chemistry USSR (English Translation), 1973, vol. 9, # 3, p. 452 - 453