Memory of chirality: enantioselective alkylation reactions at an asymmetric carbon adjacent to a carbonyl group

1991 ◽  
Vol 113 (25) ◽  
pp. 9694-9696 ◽  
Author(s):  
Takeo Kawabata ◽  
Kiyoshi Yahiro ◽  
Kaoru Fuji
Keyword(s):  
Carbonyl Group ◽  
Memory Of Chirality ◽  
Enantioselective Alkylation ◽  
Alkylation Reactions ◽  
Asymmetric Carbon

scholarly journals (R,S)-2-{[4-(4-Methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl] thio}-1-phenyl-1-ethanol

Molbank ◽  
10.3390/m1231 ◽  
2021 ◽  
Vol 2021 (2) ◽  
pp. M1231
Author(s):  
Flavius-Gabriel Wurfer ◽  
Valentin Badea
Keyword(s):  
Nmr Spectroscopy ◽  
Carbonyl Group ◽  
Elemental Analysis ◽  
Secondary Alcohol ◽  
2D Nmr ◽  
15N Nmr ◽  
15N Nmr Spectroscopy ◽  
Alkaline Conditions ◽  
Asymmetric Carbon

4-(4-Methoxyphenyl)-5-phenyl--4H-1,2,4-triazole-3-thiol (4) was alkylated to 2-{[4-(-4-methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenylethan-1-one (5) in alkaline conditions using 2-bromo-1-phenylethanone. The alkylated compound (5) was reduced at the carbonyl group to the corresponding racemic secondary alcohol with an asymmetric carbon, (R,S)-2-{[4-(4-methoxyphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol (6). Both synthesized compounds, ketone (5) and secondary alcohol (6), are new and have not been reported yet in the literature. All the synthesized compounds were characterized by IR, 1D and 2D NMR 1H-1H, 1H-13C and 1H-15N-NMR spectroscopy and by elemental analysis.

Memory of chirality in rebound cyclizations of α-amide radicals

2013 ◽  
Vol 91 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Aniruddha Sasmal ◽  
Tsuyoshi Taniguchi ◽  
Peter Wipf ◽  
Dennis P. Curran
Keyword(s):  
Carbonyl Group ◽  
Tert Butyl ◽  
Tributyltin Hydride ◽  
Memory Of Chirality ◽  
Amide Carbonyl ◽  
Amide Carbonyl Group

Reduction of (S)-N-(2-bromoallyl)-N-(tert-butyl)-2-methyl-3-phenylpropanamide with tributyltin hydride provides (3S,4S)-3-benzyl-1-(tert-butyl)-3,4-dimethylpyrrolidin-2-one with about 80% retention of chirality at the stereocenter adjacent to the amide carbonyl group. This memory of chirality is suggested to occur by transfer of chirality from a stereocenter to an axis, then from the axis back to a new stereocenter.

scholarly journals (R,S)-2-{[4-(4-Methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol

Molbank ◽  
10.3390/m1241 ◽  
2021 ◽  
Vol 2021 (3) ◽  
pp. M1241
Author(s):  
Vladislav-Silvestru Valicsek ◽  
Valentin Badea
Keyword(s):  
Nmr Spectroscopy ◽  
Carbonyl Group ◽  
Elemental Analysis ◽  
Secondary Alcohol ◽  
15N Nmr ◽  
15N Nmr Spectroscopy ◽  
Alkaline Conditions ◽  
Asymmetric Carbon

4-(4-Methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-thiol (4) was alkylated to 2-{[4-(4-methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenylethan-1-one (5) in alkaline conditions using 2-bromo-1-phenylethanone. The alkylated compound (5) was reduced at the carbonyl group to the corresponding racemic secondary alcohol with an asymmetric carbon, (R,S)-2-{[4-(4-methylphenyl)-5-phenyl-4H-1,2,4-triazol-3-yl]thio}-1-phenyl-1-ethanol (6). Both synthesized compounds, ketone (5) and secondary alcohol (6), are new and have not yet been reported in the literature. All the synthesized compounds were characterized by IR, 1D and 2D 1H-1H, 1H-13C and 1H-15N NMR spectroscopy and by elemental analysis.

scholarly journals CuH-Catalyzed Enantioselective Alkylation of Indole Derivatives with Ligand-Controlled Regiodivergence

2018 ◽  
Author(s):  
Yuxuan Ye ◽  
Seoung-Tae Kim ◽  
Jinhoon Jeong ◽  
Mu-Hyun Baik ◽  
Stephen L. Buchwald
Keyword(s):  
Organic Chemistry ◽  
Organic Synthesis ◽  
Density Functional ◽  
Copper Hydride ◽  
Indole Derivatives ◽  
Functional Theory ◽  
Ligand Density ◽  
Significant Challenge ◽  
Enantioselective Alkylation ◽  
Alkylation Reactions

<b>Enantioenriched molecules bearing indole-substituted stereocenters form a class of privileged compounds in biological, medicinal, and organic chemistry. Thus, the development of methods for asymmetric indole alkylation is highly valuable in organic synthesis. Traditionally, achieving N-selectivity in indole alkylation reactions is a significant challenge, since there is an intrinsic preference for alkylation at C3, the most nucleophilic position. Furthermore, selective and predictable access to either N- and C3-alkylated chiral indoles using catalyst control has been a long-standing goal in indole functionalization. Herein, we report a ligand-controlled regiodivergent synthesis of N- and C3-alkylated chiral indoles that relies on a polarity reversal strategy. In contrast to conventional alkylation reactions in which indoles are employed as nucleophiles, this transformation employs electrophilic indole derivatives, N-(benzoyloxy)indoles, as coupling partners. N- or C3-alkylated indoles are prepared with high levels of regio- and enantioselectivity using a copper hydride catalyst. The regioselectivity is governed by the use of either DTBM-SEGPHOS or Ph-BPE as the supporting ligand. Density functional theory (DFT) calculations are conducted to elucidate the origin of the ligand-controlled regiodivergence.</b>

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