- Diastereoselectivity control of the radical carboazidation of substituted methylenecyclohexanes
-
A systematic study of the diastereoselectivity of the radical carboazidation of methylenecyclohexane derivatives is presented. Several substitution patterns leading to a high level of stereocontrol have been identified. Axial attack is the preferred reaction pathway for cyclohexyl radicals, and excellent stereoselectivities can be obtained by introducing an axial substitutent at position 2. In this case, a second equatorial substituent at position 2 may be tolerated without a large detrimental effect on the diastereoselectivity. Finally, a high level of equatorial attack is observed with a very bulky substituent at position 2.
- Cren, Sylvaine,Schar, Pascal,Renaud, Philippe,Schenk, Kurt
-
supporting information; experimental part
p. 2942 - 2946
(2009/09/06)
-
- Design and synthesis of 2,3,4,9-tetrahydro-1H-carbazole and 1,2,3,4-tetrahydro-cyclopenta[b]indole derivatives as non-nucleoside inhibitors of hepatitis C virus NS5B RNA-dependent RNA polymerase
-
A novel class of HCV NS5B RNA dependent RNA polymerase inhibitors containing 2,3,4,9-tetrahydro-1H-carbazole and 1,2,3,4-tetrahydro-cyclopenta[b] indole scaffolds were designed and synthesized. Optimization of the aromatic region showed preference for 5,8
- Gopalsamy, Ariamala,Shi, Mengxiao,Ciszewski, Gregory,Park, Kaapjoo,Ellingboe, John W.,Orlowski, Mark,Feld, Boris,Howe, Anita Y. M.
-
p. 2532 - 2534
(2007/10/03)
-
- Studies on diastereoselective reduction of cyclic β-ketoesters with boron hydrides. Part 4: The reductive profile of functionalized cyclohexanone derivatives
-
Reduction of 2-allyl-2-carboalkoxycyclohexanones (3d-f), 2-propyl-2-carboethoxycyclohexanone (3g) and 2-benzyl-2- carboethoxycyclohexanone (3h) with boron hydrides in the presence and absence of several chelating agents were studied. Molecular modeling studies using semiempirical PM3 method were performed in order to find a suitable explanation of the diastereoselection of ketone carbonyl faces during the reductive process, which yielded trans-2-allyl-2-carboethoxycyclohexanol (6e) and cis-2-allyl-2-carboethoxycyclohexanol (7e) in good diastereomeric excess by using inexpensive sodium and tetrabutylammonium borohydrides.
- Fraga, Carlos A.M.,Teixeira, Lis Helena P.,Menezes, Carla Maria De S.,Sant'Anna, Carlos Mauricio R.,Ramos, Maria Da Concei??o K.V.,De Aquino Neto, Francisco R.,Barreiro, Eliezer J.
-
p. 2745 - 2755
(2007/10/03)
-
- Electroorganic Chemistry. 124. Electroreductive Intramolecular Coupling of α-(ω-Bromoalkyl) β-Keto Esters
-
Intramolecular coupling occurs when cyclic α-(bromomethyl) β-keto esters are electrochemically reduced in the presence of trimethylsilyl chloride and one-carbon ring-enlarged products are obtained in reasonable yields.Electroreduction of α-(γ-bromopropyl) β-keto esters also affords the corresponding five-membered cyclized products and/or the corresponding ring-opened compounds.The ease of ring opening of the cyclized products is highly influenced by their stereoconfiguration.Electroreduction of α-(β-bromoethyl) β-keto ester gives the product formed by the reductive elimination of the bromoethyl group whereas α-(δ-bromobutyl) β-keto ester yields the product of the reductive elimination of bromine.This electroreductive intramolecular coupling is initiated by the reduction of the carbon-bromine bond and proceeds through a carbanion intermediate.
- Shono, Tatsuya,Kise, Naoki,Uematsu, Nobuyuki,Morimoto, Shinji,Okazaki, Eiichi
-
p. 5037 - 5041
(2007/10/02)
-
- NOVEL FREE RADICAL RING-EXPANSION REACTIONS
-
A novel free radical initiated ring expansion of haloalkyl β-keto esters is described.Following alkylation of the β-keto ester with the appropriate dihalide, the resulting halide is treated at reflux with tri-n-butyltin hydride.Rearrangement to the homolo
- Dowd, Paul,Choi, Soo-Chang
-
-
- ENZYMATIC RESOLUTION OF RACEMIC LACTONES
-
PPL, HLE or PLE enzymatic resolution of racemic γ, δ and ε-lactones gives optically active lactones (ee: 60 to 90percent).
- Blanco, L.,Guibe-Jampel, E.,Rousseau, G.
-
p. 1915 - 1918
(2007/10/02)
-