80595-59-1Relevant academic research and scientific papers
Asymmetric Wittig reaction of chiral arsonium ylides - I. Asymmetric olefination of 4-substituted cyclohexanones
Dai, Wei-Min,Wu, Jinlong,Huang, Xian
, p. 1979 - 1982 (1997)
Asymmetric Wittig-type olefination of 4-substituted cyclohexanones with chiral ligand-modified stable arsonium ylides has been examined. The 8-phenylmenthol-derived chiral arsonium ylide of 4 reacted with prochiral ketones 9a-d at -15°C to give the 4-substituted cyclohexylideneacetates 11a-d in 58-69% yield and in up to 80% diastereomeric excess (de).
Asymmetric Sommelet-Hauser rearrangement of N-benzylic ammonium salts
Tayama, Eiji,Kimura, Hiroshi
, p. 8869 - 8871 (2008/09/19)
(Chemical Equation Presented) [2,3] over [1,2]: The asymmetric Sommelet-Hauser rearrangement of an ammonium salt derived from N-benzylic proline-derived or N-benzylic glycine (-)-8-phenylmenthol ester is shown to proceed with remarkably high levels of stereoselectivity. The method provides unique and efficient access to optically active α-aryl amino acid derivatives.
Exceptionally mild, high-yield synthesis of α-fluoro acrylates
Zajc, Barbara,Kake, Shivani
, p. 4457 - 4460 (2007/10/03)
Novel achiral and chiral alkyl α-(1,3-benzothiazol-2-ylsulfonyl)- α-fluoroacetates can be readily synthesized by metalation-fluorination of (1,3-benzothiazol-2-ylsulfonyl)acetates. DBU-mediated condensations of these fluorinated synthons with aldehydes proceed in a facile manner at 0 °C or at room temperature giving high yields of α-fluoro acrylates. Ketones are unreactive under these conditions. The presence of fluorine renders the synthon substantially more reactive compared to the unfluorinated analogue. Reactivity of α-(1,3-benzothiazol-2-ylsulfonyl)-α-fluoroacetate and the Horner-Wadsworth-Emmons reagent (EtO)2P(O)CHFCOOEt has also been compared.
Asymmetric induction in Darzens condensation by means of (-)-8-phenylmenthyl and (-)-menthyl auxiliaries
Takagi, Ryukichi,Kimura, Jyunji,Shinohara, Yoshihiro,Ohba, Yuko,Takezono, Kyoko,Hiraga, Yoshikazu,Kojima, Satoshi,Ohkata, Katsuo
, p. 689 - 698 (2007/10/03)
Asymmetric Darzens condensation of benzaldehyde and various ketones has been investigated. The condensation of acetophenone, propiophenone and symmetric ketones with (-)-8-phenylmenthyl halogenoacetates 3a,b afforded the corresponding glycidic esters cis-12, cis-13 and 15-19 in 77-96% de, respectively, as the major products. Aza-Darzens condensation between N-benzylideneaniline and 3a occurred to give the trans-aziridine 21 as the major isomer in >85% de. The stereochemistry of the major diastereoisomers of cis-12 and 18 was confirmed by their conversion into the known optically active diols 22 and 24. The configuration of the major product of cis-12 was determined to be 2R,3R and that of 18 to be 2R. The geometric and disastereofacial selectivities were understandable in terms of the open-chain or non-chelated antiperiplanar transition state model in the initial aldol-type reaction.
Remarkable examples of double diastereodifferentiation: Application to the eudistomin and eudistomidin alkaloids
Polniaszek, Richard P.,Bell, Stephanie J.
, p. 575 - 578 (2007/10/02)
Nucleophilic addition of chiral enolates 1 and ent-1 with chiral iminium ion 2a occur with total stereochemical control.
Synthesis of an optically pure 3-unsubstituted β-lactam using an asymmetric reformatsky reaction and its conversion to cholesterol absorption inhibitors
Shankar,Kirkup,McCombie,Clader,Ganguly
, p. 4095 - 4098 (2007/10/03)
Asymmetric induction by several chiral alcohols in the reaction of their bromoacetates with imines in the presence of activated Zn (Reformatsky reaction) was studied. Trans-2-phenlcyclohexanol and phenyl menthol gave β- lactam 9, obtained by cyclizing the diastereoisomeric β-aminoesters 8, in > 99%ee. The resulting chiral 3-unsubstituted azetidin-2-one 9 was converted to 3-substituted products 11, 12, and 13 which exhibit cholesterol absorption inhibitory activity.
High diastereofacial selectivity in the 1,3-dipolar cycloaddition of chiral azomethine ylides
Deprez,Royer,Husson
, p. 1189 - 1192 (2007/10/02)
Excellent diastereofacial and endo/exo stereoselectivities have been obtained in cycloaddition of the chiral azomethine ylide generated from 4-phenyloxazolidine acetic acid (-)-8-phenylmenthyl ester 1e.
PREPARATION OF THREE DIASTEREOISOMERS OF 2-(1-METHYL-1-PHENYLETHYL)-5-METHYLCYCLOHEXAN-1-OL FROM (R)-(+)-PULEGONE
Cervinka, Otakar,Svatos, Ales,Masojidkova, Milena
, p. 491 - 498 (2007/10/02)
New isolation of (1R,2S,5R)-(-)-2-(1-methyl-1-phenylethyl)-5-methylcyclohexan-1-ol ((-)-8-phenylmenthol, Ia), prepared from (R)-(+)-pulegone, is described.The method consists in the preparation of phenylcarbamate of Ia and its transesterification with ethanol.Further two diastereoisomers of (-)-8-phenylmenthol were isolated: the (1S,2R,5R)-isomer IIa and the (1R,2R,5R)-isomer IIIa.Compounds Ia, IIa and IIIa were converted into their respective glyoxylates Ic, IIc and IIIc.
ENANTIOSELECTIVE SYNTHESIS OF OPTICALLY PURE S-ISOSERINE
Solladie-Cavallo, A.,Khiar, N.
, p. 2189 - 2192 (2007/10/02)
KF-promoted addition of nitromethane on (-)-8-phenylmethyl glyoxylate monohydrate affords, after one purification, optically pure (-)S isoserine in about 50percent yield.
ASYMMETRIC INDUCTION IN THE ENE REACTION OF GLYOXYLATE ESTERS OF 8-PHENYLMENTHOL
Whitesell, James K.,Bhattacharya, Apurba,Buchanan, Charles M.,Chen, H. H.,Deyo, Don,et al.
, p. 2993 - 3002 (2007/10/02)
We recently communicated (J.K.Whitesell, A.Bhattacharya, D.A.Aguilar and K.Henke, J.Chem.Soc.Chem.Commun. 989 (1982)) a highly efficient and effective method for the control of absolute stereochemistry through asymmetric induction in the ene reaction the chiral glyoxylate 1 with alkenes.We now have accumulated sufficient information on this process in terms of both its mechanistic details as well as its scope and applicability to a variety of situations that warrants a more complete presentation of these reactions.
