153489-62-4Relevant academic research and scientific papers
Diastereoselective Rhodium Catalyzed [4 + 2] Cycloisomerization of Allenes
Li, Jun,Gilbertson, Scott R.
, p. 2911 - 2914 (2021)
A diastereoselective [4 + 2] cycloisomerization of asymmetric allenyl dienes is reported. The asymmetric dienyl allenes are synthesized using the method reported by Ma. These substrates readily undergo diastereoselective intramolecular rhodium catalyzed [4 + 2] cycloisomerization analogous to thermal intramolecular Diels-Alder reactions. Overall, 29 examples are presented with tethers possessing nitrogen, oxygen, and carbon. Diastereoselectivities range from 99:1 to 90:10 in most examples.
Enantio- And Diastereodivergent Construction of 1,3-Nonadjacent Stereocenters Bearing Axial and Central Chirality through Synergistic Pd/Cu Catalysis
Huo, Xiaohong,Ma, Shengming,Xiao, Junzhe,Zhang, Jiacheng,Zhang, Wanbin,Zhao, Ling
supporting information, p. 12622 - 12632 (2021/08/31)
In contrast to the widely explored methods for the asymmetric synthesis of molecules bearing a single stereocenter or adjacent stereocenters, the concurrent construction of 1,3-stereogenic centers in an enantio- and diastereoselective manner remains a challenge, especially in acyclic systems. Herein, we report an enantio- and diastereodivergent construction of 1,3-nonadjacent stereocenters bearing allenyl axial and central chirality through synergistic Pd/Cu-catalyzed dynamic kinetic asymmetric allenylation with racemic allenylic esters. The protocol is suitable for a wide range of substrates including the challenging allenylic esters with less sterically bulky substituents and provided chiral allenylic products bearing 1,3-nonadjacent stereocenters with high levels of enantio- and diastereoselectivities (up to >20:1 dr and >99% ee). Furthermore, several representative transformations involving axial-to-central chirality transfer were conducted, affording useful structural motifs containing nonadjacent stereocenters in a diastereodivergent manner.
Enantioselective synthesis of allenes by catalytic traceless petasis reactions
Jiang, Yao,Diagne, Abdallah B.,Thomson, Regan J.,Schaus, Scott E.
, p. 1998 - 2005 (2017/02/15)
Allenes are useful functional groups in synthesis as a result of their inherent chemical properties and established reactivity patterns. One property of chemical bonding renders 1,3-substituted allenes chiral, making them attractive targets for asymmetric synthesis. While there are many enantioselective methods to synthesize chiral allenes from chiral starting materials, fewer methods exist to directly synthesize enantioenriched chiral allenes from achiral precursors. We report here an asymmetric boronate addition to sulfonyl hydrazones catalyzed by chiral biphenols to access enantioenriched allenes in a traceless Petasis reaction. The resulting Mannich product from nucleophilic addition eliminates sulfinic acid, yielding a propargylic diazene that performs an alkyne walk to afford the allene. Two enantioselective approaches have been developed; alkynyl boronates add to glycolaldehyde imine to afford allylic hydroxyl allenes, and allyl boronates add to alkynyl imines to form 1,3-alkenyl allenes. In both cases, the products are obtained in high yields and enantioselectivities.
General CuBr2-catalyzed highly enantioselective approach for optically active allenols from terminal alkynols
Huang, Xin,Cao, Tao,Han, Yulin,Jiang, Xingguo,Lin, Weilong,Zhang, Jiasheng,Ma, Shengming
supporting information, p. 6956 - 6959 (2015/04/22)
Here, we show a CuBr2-catalyzed approach for a highly enantioselective synthesis (93-99% ee) of allenols from aldehydes and terminal alkynols with the absolute configuration being controlled by applying readily available (R)- or (S)-α,α-dipheny
OPTICALLY ACTIVE AXIALLY CHIRAL ALPHA-ALLENIC ALCOHOL, SYNTHESIS METHOD AND USE THEREOF
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Paragraph 0016-0018, (2015/04/22)
The present invention relates to an optically active axially chiral α-allenic alcohol, a synthetic method and use thereof. A method of preparing a high optically active chiral α-allenic alcohol by using propargyl alcohol, aldehyde and chiral α,α-diphenyl-L-prolinol under the protection of tert-butyldimethylsilyl with a mediator zinc bromide. The axially chiral α-allenic alcohol has the structural formula (I). The method of the present invention has the following advantages: the synthesis route is short, operations are simple, raw materials are readily available, separation and purification are convenient, the substrate has high generality, the total yield is high, and enantioselectivity and diastereoselectivity are high. The high optically active axially chiral α-allenic alcohol synthesized by adopting the method of the present invention can conveniently synthesize 2,5-dihydrofuran compounds having central chirality via complete chirality transfer, and at the same time can further be used to synthesize axially chiral allenic amine and allenic malonate compounds without reacemization.
Tert-butyldimethylsilyl-directed highly enantioselective approach to axially chiral α-allenols
Ye, Juntao,Fan, Wu,Ma, Shengming
supporting information, p. 716 - 720 (2013/02/23)
A highly efficient and enantioselective synthesis of axially chiral α-allenols was realized in practical yields with 96-99 % ee or de from TBS-protected propargylic alcohols, aldehydes, and a commercially available, inexpensive, chiral, secondary amine (S)-α,α-diphenylprolinol or its enantiomer followed by desilylation. The easily removable TBS group not only acts as a protecting group, but also as a possible sterically directing group for the excellent enantioselectivity and in situ prevention of possible allene racemization. Copyright
A direct synthesis of allenes by a traceless petasis reaction
Mundal, Devon A.,Lutz, Kelly E.,Thomson, Regan J.
, p. 5782 - 5785 (2012/05/07)
A one-pot synthesis of allenes by the 2-nitrobenzenesulfonylhydrazide- mediated coupling of hydroxyaldehydes or ketones with alkynyl trifluoroborate salts is reported. This mild process involves in situ formation of a sulfonylhydrazone that reacts with alkynyl trifluoroborates to generate a transient propargylic hydrazide species. Decomposition of this unstable hydrazide via an intermediate monoalkyldiazine produces the allene products through an alkene walk mechanism.
Dynamic kinetic asymmetric allylic alkylations of allenes
Trost, Barry M.,Fandrick, Daniel R.,Dinh, Diana C.
, p. 14186 - 14187 (2007/10/03)
The dynamic kinetic asymmetric allylic alkylations of racemic allene acetates has been developed with the DACH-phenyl Trost ligand 2 to give general access to allenes with high enantiomeric excess (84-95%) for both malonate and amine nucleophiles. Further
