- Aziridinium ions from phenylglycinol - A new approach to the synthesis of chiral diamines
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A new two-step method [(i) N,N-dialkylation; (ii) aziridinium ion formation followed by amine attack] for the synthesis of chiral diamines from phenylglycinol is described. sequentially without isolation of the intermediate amino alcohols to give diamines in good yields (62-76%). An improved protocol for the N,N-dialkylation of phenylglycinol is also reported.
- De Sousa, Simon E.,O'Brien, Peter
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- Catalytic asymmetric syntheses of ICI-199441 and CP-99994 using nitro-Mannich reaction
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Catalytic asymmetric syntheses of ICI-199441 and CP-99994 were achieved using the nitro-Mannich reaction as a key step.
- Tsuritani, Natsuko,Yamada, Ken-Ichi,Yoshikawa, Naoki,Shibasaki, Masakatsu
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p. 276 - 277
(2007/10/03)
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- Synthesis of chiral non-racemic 1,2-diamines from O-acetyl mandelic acid: Application in enantioselective deprotonation of epoxides and diethylzinc addition to aldehydes
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A variety of 1,2-diamines were synthesized from readily available O-acetyl mandelic acid. These diamines were used in the synthesis of key intermediates for the preparation of (-)-utenone A and carbovir involving enantioselective deprotonation of epoxides. The addition of Et2Zn catalysed by some of these diamines was also studied and although ees were not high, some interesting observations were made in the outcome of the stereochemistry of the product.
- Saravanan,Bisai, Alakesh,Baktharaman,Chandrasekhar,Singh, Vinod K
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p. 4693 - 4706
(2007/10/03)
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- Two expedient methods for the preparation of chiral diamines
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A study on the development of methodology for the synthesis of chiral diamines is reported. Two synthetic approaches are described both of which involve the generation and subsequent reaction of aziridinium ions. One of the methods is a one-pot preparatio
- De Sousa, Simon E.,O'Brien, Peter,Poumellec, Pierre
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p. 1483 - 1492
(2007/10/03)
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- An efficient synthesis of chiral nonracemic diamines: Application in asymmetric synthesis
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A variety of chiral diamines have been synthesized from optically active mandelic acid in an efficient manner. The chiral nonracemic lithium amide base derived from one of the diamines has been used in formal asymmetric synthesis of natural products such as (-)-utenone A and (-)-carbovir.
- Saravanan, Parthasarathy,Singh, Vinod K.
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p. 167 - 170
(2007/10/03)
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- Two useful methods for the preparation of (R)- and (S)-N-methyl-1-phenyl-2-(1-pyrrolidinyl)ethanamine
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Two methods for the efficient preparation of either enantiomer of the synthetically useful diamine N-methyl-1-phenyl-2-(1-pyrrolidinyl)ethanamine are reported. Each of the methods starts from readily available materials (styrene oxide or phenylglycinol) a
- De Sousa, Simon E.,O'Brien, Peter,Poumellec, Pierre
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p. 2613 - 2618
(2007/10/03)
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- Enantioselective deprotonation of cyclohexene oxide to (R)-2-cyclohexen- 1-ol
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The reaction of cyclohexene oxide with homochiral lithium amides, prepared from (S)-phenylglycine and (S)-valine has been studied and (R)-2-cyclohexen- 1-ol 3 was prepared in a maximum of 72% ee. The optical purity was determined by 1H NMR measurement of the α-methoxy-α-(trifluoromethyl)phenyl acetic acid (MTPA) derivative of the corresponding alcohol.
- Bhuniya,Singh
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p. 1475 - 1481
(2007/10/02)
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- Enantioselective conjugate addition to cyclic enones with scalemic lithium organo(amido)cuprates, part IV. Relationship between ligand structure and enantioselectivity
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Scalemic lithium amides derived from primary and secondary amines react with organocopper compounds in ether or dimethyl sulfide to form lithium organo(amido)cuprates capable of enantioselective conjugate addition to 2-cycloalkenones. The most successful heterocuprate, in which the chiral ligand is (S)-N-methyl-1-phenyl-2-(1-piperidinyl)ethanamine, (S)-MAPP, 13, reacts with cyclic enones to form products with up to 97% ee. Nonlinear asymmetric induction was observed with the cuprate formed from ligand 13.
- Rossiter, Bryant E.,Eguchi, Masakatsu,Miao, Guobin,Swingle, Nicole M.,Hernandez, Amelia E.,Vickers, Denise,Fluckiger, Ezdan,Greg Patterson,Vasavi Reddy
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p. 965 - 986
(2007/10/02)
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- Structure/Activity Studies Related to 2-(3,4-Dichlorophenyl)-N-methyl-N-acetamides: A Novel Series of Potent and Selective κ-Opioid Agonists
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This paper describes the synthesis of a series of N-acetamides 1, variously substituted at the carbon adjacent to the amide nitrogen (C1), and related analogues, together with their biological evaluation as opioid κ agonists.In the first part of the study, the variants in N-acyl, N-alkyl, and amino functions were explored when the substituent at C1 was 1-methylethyl and the optimum was found to be exemplified by 2-(3,4-dichlorophenyl)-N-methyl-N-acetamide (13).Subsequently, racemic or chiral amino acids were used to introduce other alkyl and aryl substituents at C1 of the ethyl linking moiety.A series of potent compounds, bearing substituted-aryl groups at C1, were discovered, typified by 2-(3,4-dichlorophenyl)-N-methyl-N-acetamide (48), which was 5-fold more active as the racemate than 13 in vitro and exhibited potent naloxone-reversible analgesic effects (ED50 = 0.04 mg/kg sc) in a mouse abdominal constriction model.
- Barlow, Jeffrey J.,Blackburn, Thomas P.,Costello, Gerard F.,James, Roger,Count, David J. Le,et al.
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p. 3149 - 3158
(2007/10/02)
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- 2-(3,4-Dichlorophenyl)-N-methyl-N-acetamides: The Use of Conformational Analysis in the Development of a Novel Series of Potent Opioid κ Agonists
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This paper describes the synthesis of a series of N-acetamides (1), methylated at C1 and/or C2 of the ethyl linking group, and their biological evaluation as opioid κ agonists.Conformational analysis of corresponding desaryl analogues 2 suggested that only those compounds capable of occupying an energy minimum close to that of the known κ agonist N-acetamide U-50488 might possess κ agonist properties.Starting from chiral amino acids, other alkyl and aryl substituents were introduced at C1 of the ethyl-linking moiety, giving compounds capable of adopting the same conformation as U-50488.The most potent of these, 2-(3,4-dichlorophenyl)-N-methyl-N-acetamide (8), was 146-fold more active than U-50488 in vitro in the mouse vas deferens model and exhibited potent naloxone-reversible analgesic effects (ED50 = 0.004 mg/kg sc) in an abdominal constriction model.
- Costello, Gerard F.,James, Roger,Shaw, John S.,Slater, Anthony M.,Stutchbury, Neil C. J.
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p. 181 - 189
(2007/10/02)
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