5700-74-3Relevant academic research and scientific papers
Organocatalytic Enantioselective Continuous-Flow Cyclopropanation
Llanes, Patricia,Rodríguez-Escrich, Carles,Sayalero, Sonia,Pericàs, Miquel A.
supporting information, p. 6292 - 6295 (2016/12/23)
A set of six solid-supported diarylprolinol catalysts (varying on the anchoring strategy and the type of polymeric support) has been prepared and applied to the enantioselective cyclopropanation reaction. The selected candidate allows implementation of a long flow experiment (48 h) and generates a library of 12 cyclopropanes by sequential flow experiments. The mildness and utility of the method have enabled a telescoped process in which the outstream is directly used in a Wittig flow reaction.
Diastereoselective synthesis of (R)-phenanthrenyl-9yl-[(S)-pyrrolidin-2yl)] methanol
Russo, Alessio,Fuoco, Tiziana,Lattanzi, Alessandra
, p. 784 - 790 (2013/02/25)
A four-step synthesis of sterically demanding (R)-phenanthren-9-yl-[(S)- pyrrolidin-2-yl] methanol has been easily accomplished starting from L-proline in high diastereoselectivity. These compounds are potentially useful ligands in metal-catalyzed reactio
Stereocontrolled solid-phase synthesis of oligonucleoside H-phosphonates by an oxazaphospholidine approach
Iwamoto, Naoki,Oka, Natsuhisa,Sato, Terutoshi,Wada, Takeshi
supporting information; experimental part, p. 496 - 499 (2009/04/14)
(Chemical Equation Presented) Stereodefined oligonucleoside H-phosphonates were synthesized on a solid support using diastereopure nucleoside 3′-O-oxazaphospholidine monomers. Several stereodefined backbone-modified analogues were obtained with the oligonucleoside H-phosphonates as precursors (see scheme; BPRO = protected nucleobase, DMTr = 4,4′- dimethoxytrityl, Th = thymin-1-yl, TfO- = triflate).
Synthesis and resolution of 2,2-dimethyl-1,3-diphenyl-1,3-propanediol, a new C2-symmetric and conformationally rigid acyclic diol
Bhowmick,Prasad,Joshi
, p. 851 - 855 (2007/10/03)
Diastereomerically pure (+)- and (-)-2,2-dimethyl-1,3-diphenyl-1,3-propanediols were synthesized starting from diethyl malonate and resolved through diesters of (-)-camphanic acid and also N-carbethoxy-L-proline. The absolute configuration of the (-)-enantiomer was established by X-ray crystallography.
Flash vacuum pyrolysis of stabilised phosphorus ylides. Part 17. Preparation of aliphatic amino acid derived γ-alkoxycarbonyl-amino-β-oxo ylides and pyrolysis to give α,β-acetylenic γ-amino acid and GABA analogues
Aitken, R. Alan,Karodia, Nazira,Massil, Tracy,Young, Robert J.
, p. 533 - 541 (2007/10/03)
A series of eleven α-aminoacyl stabilised phosphorus ylides 9-19 have been prepared by condensation of N-alkoxycarbonyl protected amino acids with Ph3P = CHCO2Et using a carbodiimide peptide coupling reagent. Upon flash vacuum pyrolysis at 600 °C, these undergo extrusion of Ph3PO to give the corresponding α,β-acetylenic γ-amino esters 21-29, 33 and 34 in moderate yield. In two cases the terminal alkynes 30 and 31 are also formed. The β-aminoacyl ylide 20 from β-alanine similarly gives the α,β-acetylenic δ-amino ester 35 upon pyrolysis. Regioselective addition of HBr to the triple bond of one acetylenic ester 25 was observed giving a mixture of E and Z α-bromoacrylates 36. Hydrogenation of the N-Cbz acetylenic esters 21-23 and 33 results in N-deprotection and hydrogenation of the triple bond to afford the chiral GABA analogues 37-40 in 70 ->95% ee as determined by 19F NMR of their Mosher amides. Fully assigned 13C NMR spectra of all the ylides and acetylenic ester derivatives are presented.
Convenient method for the synthesis of chiral α,α-diphenyl-2-pyrrolidinemethanol
Kanth, J. V. Bhaskar,Periasamy, Mariappan
, p. 5127 - 5132 (2007/10/02)
A simplified, convenient synthesis of chiral α,α-diphenyl-2-pyrrolidine-methanol involving one step N-and O-protection of S-proline using ethylchloroformate followed by Grignard addition-alkaline hydrolysis (KOH/CH3OH) is described.
Synthesis of Chiral N-Protected α-Amino-β-Diketones from α-Diazoketones Derived from Natural Amino Acids
Ye, Tao,McKervey, M. Anthony
, p. 8007 - 8022 (2007/10/02)
α-Diazoketols, prepared by condensation of aldehydes or ketones with lithiated optically active α-diazoketones derived from natural amino acids, rearrange to homochiral α-amino-β-diketones on treatment with rhodium(II) acetate.
Asymmetric Synthesis of Optically Active threo- and erythro-Pyrrolidinylbenzyl Alcohol by the Highly Stereospecific Arylation of (S)-Proline and the Subsequent Highly Diastereoselective Reduction of the α-Amino Ketone
Ookawa, Atsuhiro,Soai, Kenso
, p. 1465 - 1472 (2007/10/02)
Optically active α-amino phenyl ketones in 92-94percent enantiomeric excess (e.e.) were obtained from the stereospecific arylation of (S)-proline or its derivatives by Friedel-Crafts reaction of by Grignard reaction.The subsequent complementary diastereoselective reductions of the α-amino ketone afforded respectively (S)- and (R)-α-benzyl alcohol in 93-100percent e.e. and in 100percent diastereoisomeric excess.The stereochemical course of the reduction of the α-amino ketone is discussed.
Catalytic Asymmetric Induction. Highly Enantioselective Addition of Dialkylzincs to Aldehydes Using Chiral Pyrrolidinylmethanols and Their Metal Salts
Soai, Kenso,Ookawa, Atsuhiro,Kaba, Tatsuya,Ogawa, Kazuo
, p. 7111 - 7115 (2007/10/02)
A series of chiral pyrrolidinylmethanols were synthesized from (S)-proline.Optically active secondary alcohols (R and S enantiomers, respectively) in up to 100percent enantiomeric excess (ee) were obtained in high yields from the enantioselective addition of dialkylzincs to aldehydes catalyzed by 2-5 mol percent of chiral pyrrolidinylmethanols.The sense of the asymmetric induction and the degrees of enantioselectivities were highly dependent on the structure of the catalysts. (+)-DPMPM (3, tertiary amino tertiary alcohol) catalyzed the reaction of aryl, α,β-unsaturated, and aliphatic aldehydes to afford (S) alcohols in high ee's.When the lithium salt of 3 was employed as catalyst in the reactions of aryl and α,β-unsaturated aldehydes, the ee's of (S) alcohols reached 100percent.On the other hand, (-)-erythro-PNPM (10, tertiary amino secondary alcohol) afforded (R) alcohols in high ee (100percent ee).The steric course of the reaction is discussed.
