- ELECTROREDUCTIVE CYCLIZATION. A COMPARISON OF THE ELECTROCHEMICAL AND ANALOGOUS CHEMICAL (MIRC) REACTION
-
Several examples which illustrate the contrasting and complementary aspects of electroreductive cyclization and MIRC reactions are presented.A brief mechanistic discussion of the electrochemical reaction is given and two examples of the use of an electroc
- Nugent, Sean T.,Baizer, Manuel M.,Little, R. Daniel
-
-
Read Online
- Preparation method of 1, 1-cycloalkane dicarboxylic acid and derivatives thereof
-
The invention discloses a preparation method of 1, 1-cycloalkane dicarboxylic acid and derivatives thereof, which at least comprises the following steps of: forming a mixed system from malonic acid or derivatives thereof, dihalogenated hydrocarbon, tert-butyl alcohol salt and a solvent in a reactor; AND according to the method, the raw material conversion rate and the product selectivity are improved, and side reactions are hardly generated.
- -
-
Paragraph 0049-0052
(2021/05/05)
-
- Tetramethyl 1,1,4,4-Cyclohexanetetracarboxylate: Preparation and Conversion to Key Precursors of Fluorinated, Stereochemically Defined Cyclohexanes
-
Stereoselective low-temperature diisobutylaluminum hydride (DIBALH) reduction of the litle tetraester 3 affords trans-1,4-dialdehyde 4a as the major product.Fluorination of 4a,b, followed by additional elaboration leads to novel, 1,1,4,4-tetrasubstituted cyclohexanes bearing trans-1,4-difluoromethyl and fluoromethyl groups.The effect of ring size and number of ester substituents on the outcome of the reduction has been examined and treatment of dimethyl 1,1-cycloalkyl diesters 7a-c with excess DIBALH results in reduction of only one ester group.An entry into trans-1,4-trifluoromethylated tetrasubstituted cyclohexanes has been gained through stereoselective SF4 fluorination of 1,1,4,4-cyclohexanetetracarboxylic acid 17.Stereochemical assignments are supported by X-ray crystallographic data.
- Davis, Charles R.,Swenson, Dale C.,Burton, Donald J.
-
p. 6843 - 6850
(2007/10/02)
-
- Atom Transfer Cyclization Reactions of α-Iodo Esters, Ketones, and Malonates: Examples of Selective 5-Exo, 6-Endo, 6-Exo, and 7-Endo Ring Closures
-
The preparation and free-radical cyclization reactions of unsaturated α-iodo esters, ketones, and malonates have been investigated.For example, sunlamp irradiation of methyl 2-iodo-6-heptenoate in benzene in the presence of 10 mol percent hexabutylditin produces methyl 2-(iodomethyl)cyclopentanecarboxylate (cis and trans) and methyl 3-iodocyclohexanecarboxylate in a ratio of 93/7 in a combined yield of 86percent.The γ-iodo carbonyl products can either be isolated (in most cases) or converted in situ to deiodinated products (with Bu3SnH) or lactones (by heating).Five-, six-, or seven-membered rings selectively form, depending on chain length and alkene substitution.Terminal alkene substituents favor exo cyclization while internal alkene substituents promote endo cyclization.A preference for endo closure is also observed when there is a carbonyl group "inside" the forming ring.A detailed analysis of reaction rates indicates that these isomerizations proceed by an iodine atom transfer chain mechanism, and thus the observed selectivities are due to the kinetic substituent effects.The results contrast the thermodynamically controlled hydrogen atom transfer cyclizations of Julia.A new procedure for the removal of tin byproducts is described.
- Curran, Dennis P.,Chang, Chi-Tai
-
p. 3140 - 3157
(2007/10/02)
-
- Perkin-Markovnikov Type Reaction Initiated with Electrogenerated Superoxide Ion
-
The cyclic condensation of α,ω-dihaloalkanes with acticvated methylene of malonic acid and acetoacetic acid esters is studied using an electrogenerated superoxide ion.Two possible mechanisms for this reaction are postulated.
- Ojima, Fumihiro,Matsue, Tomokazu,Osa, Tetsuo
-
p. 2235 - 2238
(2007/10/02)
-