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。
Catalytic Enantioselective α-Ketol Rearrangement
作者:Hua Wu、Rémi Andres、Qian Wang、Jieping Zhu
DOI:10.1002/anie.201812244
日期:2019.1.8
A highly enantioselective α‐ketol rearrangement has been developed. In the presence of a chiral Cu‐bisoxazoline complex, achiral β‐hydroxy‐α‐dicarbonyls were isomerized to chiralα‐hydroxy‐β‐dicarbonyls and their bicyclic derivatives in excellent yields and enantioselectivities. Enantioenriched 2‐acyl‐2‐hydroxy cyclohexan‐1‐ones, dihydroxyhexahydrobenzofuranones, and dihydroxyhexahydro‐cycloheptafuranones
The first facile and efficient Cu-catalyzed direct coupling of unprotected propargylic diols with H-phosphine oxides was developed, providing a practical approach to access structurally diverse 2,3-bis(diarylphosphynyl)-1,3-butadienes along with the formation of two new P–Csp2 and two new C═C bonds under ligand- and base-free conditions.
(3-Hydroxy-3-methylbutyn-1-yl)cycloalkan-1-ols in the Ritter Reaction
作者:S. S. Koval'skaya、N. G. Kozlov、E. A. Dikusar
DOI:10.1023/b:rugc.0000042602.58177.2a
日期:2004.6
(3-Hydroxy-3-methylbutyn-1-yl)cycloalkan-1-ols were prepared by the action of (2-lithiooxy-2methylbutyn-3-yl)lithium on cyclopentanone, cyclohexanone, cycloheptanone, and cyclododecanone. The products react with acetonitrile under Ritter reaction conditions. Therewith, in the presence of 8 g-equiv of sulfuric acid, a 2: 1 mixture of 1-acetylamino-1-(2-acetylamino-2-methylbutyn-3-yl)cycloalkanes and 1-acetylamino-1-(3-acetylamino-3-methylbutyryl)cycloalkanes is formed, whereas in the presence of 2 g-equiv of the acid, a mixture of 1-acetylamino-1-(2-acetylamino-2-methylbutyn-3-yl)cycloalkanes and 1-acetylanuno-l(3-methyl-2-butenoyl)cycloalkanes in the same ratio.