4176-06-1Relevant academic research and scientific papers
Stereoselective Csp3?Csp2 Cross-Couplings of Chiral Secondary Alkylzinc Reagents with Alkenyl and Aryl Halides
Skotnitzki, Juri,Kremsmair, Alexander,Keefer, Daniel,Gong, Ye,de Vivie-Riedle, Regina,Knochel, Paul
, p. 320 - 324 (2019/11/26)
We report palladium-catalyzed cross-coupling reactions of chiral secondary non-stabilized dialkylzinc reagents, prepared from readily available chiral secondary alkyl iodides, with alkenyl and aryl halides. This method provides α-chiral alkenes and arenes with very high retention of configuration (dr up to 98:2) and satisfactory overall yields (up to 76 % for 3 reaction steps). The configurational stability of these chiral non-stabilized dialkylzinc reagents was determined and exceeded several hours at 25 °C. DFT calculations were performed to rationalize the stereoretention during the catalytic cycle. Furthermore, the cross-coupling reaction was applied in an efficient total synthesis of the sesquiterpenes (S)- and (R)-curcumene with control of the absolute stereochemistry.
Tandem Peterson olefination and chemoselective asymmetric hydrogenation of β-hydroxy silanes
Krajangsri, Suppachai,Wu, Haibo,Liu, Jianguo,Rabten, Wangchuk,Singh, Thishana,Andersson, Pher G.
, p. 3649 - 3653 (2019/03/28)
Here, we report the first Ir-N,P complex catalyzed tandem Peterson olefination and asymmetric hydrogenation of β-hydroxy silanes. This reaction resulted in the formation of chiral alkanes in high isolated yields (up to 99%) and excellent enantioselectivity (up to 99% ee) under mild conditions. Modification of the reaction conditions provides a choice to transform either an olefin or the β-hydroxy silane in a chemoselective manner. Additionally, based on this method, an expedient enantioselective synthesis of (S)-(+)-α-curcumene, from a simple ketone, was accomplished in two steps with 75% overall yield and 95% ee.
A asymmetric catalytic synthesis (S)- aryl curcumene method
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Paragraph 0011; 0043; 0044; 0045, (2017/08/25)
The invention discloses a method for asymmetrically catalyzing and synthesizing (S)-curcumene. According to the method, racemization 2-halogenated propionate ester serves as a starting material, under the catalysis of bis oxazoline/ cobalt, an asymmetrica
Stereospecific Hydrogenolysis of Lactones: Application to the Total Syntheses of (R)-ar-Himachalene and (R)-Curcumene
Spielmann, Kim,De Figueiredo, Renata Marcia,Campagne, Jean-Marc
, p. 4737 - 4743 (2017/05/12)
A straightforward strategy for the syntheses of curcumene and ar-himachalene is reported. Synthetic highlights include a catalytic and asymmetric vinylogous Mukaiyama reaction and a stereospecific hydrogenolysis of a tertiary benzylic center using Pd/C or Ni/Raney catalysts. Notably, using Ni/Raney, the stereoselectivity outcome (inversion vs retention) of the hydrogenolysis depends on the tertiary benzylic alcohol substitution.
Asymmetric synthesis of (R)-ar-curcumene, (R)-4,7-dimethyl-l-tetralone, and their enantiomers via cobalt-catalyzed asymmetric Kumada cross-coupling
Wu, Lin,Zhong, Jiang-Chun,Liu, Shi-Kuo,Liu, Fei-Peng,Gao, Zi-Dong,Wang, Min,Bian, Qing-Hua
, p. 78 - 83 (2015/12/31)
An efficient and concise asymmetric synthesis of (R)-(+)-ar-curcumene, (R)-4,7-dimethyl-l-tetralone, and their enantiomers was accomplished. The key step to construct the stereogenic benzylmethyl centers of these natural products is the cobalt-catalyzed a
A straightforward organocatalytic alkylation of 2-arylacetaldehydes: An approach towards bisabolanes
Gualandi, Andrea,Canestrari, Pietro,Emer, Enrico,Cozzi, Pier Giorgio
, p. 528 - 536 (2014/05/20)
A highly stereoselective organocatalytic aalkylation of 2-arylacetaldehydes with a commercially available carbenium tetrafluoroborate is described. The stereoselective alkylation was carried out in acetonitrile/ water, under air in the presence of a commercially available imidazolidinone (MacMillan's catalyst). Key intermediates for the synthesis of bisabolanes were obtained through a simple chemistry. In particular a direct, enantioselective and facile synthesis of (R)-(-)-curcumene is described.
Carboxy-directed asymmetric hydrogenation of α-alkyl-α-aryl terminal olefins: Highly enantioselective and chemoselective access to a chiral benzylmethyl center
Yang, Shuang,Zhu, Shou-Fei,Guo, Na,Song, Song,Zhou, Qi-Lin
supporting information, p. 2049 - 2052 (2014/03/21)
A carboxy-directed asymmetric hydrogenation of α-alkyl-α-aryl terminal olefins was developed by using a chiral spiro iridium catalyst, providing a highly efficient approach to the compounds with a chiral benzylmethyl center. The carboxy-directed hydrogenation prohibited the isomerization of the terminal olefins, and realized the chemoselective hydrogenation of various dienes. The concise enantioselective syntheses of (S)-curcudiol and (S)-curcumene were achieved by using this catalytic asymmetric hydrogenation as a key step.
Palladium/chiral amine co-catalyzed enantioselective β-arylation of α,β-unsaturated aldehydes
Ibrahem, Ismail,Ma, Guangning,Afewerki, Samson,C?rdova, Armando
, p. 878 - 882 (2013/02/23)
Palladium and a simple chiral amine are used as co-catalysts for the enantioselective conjugate addition of aryl boronic acids to α,β-unsaturated aldehydes (see scheme). The synthetic utility of this co-catalyzed reaction was demonstrated in the short tot
Enantioselective iridium-catalyzed hydrogenation of β,γ- unsaturated carboxylic acids: An efficient approach to chiral 4-alkyl-4-aryl butanoic acids
Song, Song,Zhu, Shou-Fei,Yang, Shuang,Li, Shen,Zhou, Qi-Lin
, p. 2708 - 2711 (2012/04/17)
Chiral acids: A highly enantioselective iridium-catalyzed hydrogenation of β,γ-unsaturated carboxylic acids is developed for the preparation of chiral 4-alkyl-4-aryl butanoic acids (see scheme). Copyright
Application of the lithiation-borylation reaction to the rapid and enantioselective synthesis of the bisabolane family of sesquiterpenes
Aggarwal, Varinder K.,Ball, Liam T.,Carobene, Simon,Connelly, Rickki L.,Hesse, Matthew J.,Partridge, Benjamin M.,Roth, Philippe,Thomas, Stephen P.,Webster, Matthew P.
, p. 9230 - 9232 (2012/09/10)
The expedient enantioselective synthesis of 5 bisabolane sesquiterpenes has been achieved using a common, one-pot lithiation-borylation reaction of secondary benzylic carbamates and either protodeboronation or oxidation to give the natural products in few
