14661-79-1

Upstream product

• 623-43-8 crotonic acid methyl ester 
• 103548-67-0 (Dimethylsulfuranyliden)essigsaeure-methylester 
• 557-91-5 1,1-Dibromoethane 
• 624-48-6 dimethyl cis-but-2-ene-1,4-dioate 

Downstream Products

• 139156-61-9 (1S,2R,3R)-2-(Methoxycarbonyl)-3-methylcyclopropane-1-carboxylic acid 
• 139156-61-9 (1R,2S,3S)-2-(Methoxycarbonyl)-3-methylcyclopropane-1-carboxylic acid 
• 14590-52-4 (1S,2S)-(+)-trans-2-methylcyclopropanecarboxylic acid 

Relevant academic research and scientific papers

Cyclopropanediamines, 3. - Pure Diastereomers of 1,2-Cyclopropanedicarboxylic Acids and Derivatives

Efficient preparations of pure diastereomers of dimethyl 1,2-cyclopropanedicarboxylates 2, dicarboxylic acids 3, dicarbonyl dichlorides 4, and dihydrazides 5 are reported.Mixtures of diastereomers of dimethyl dicarboxylates 2a, b, d, e are obtained from α,β-unsaturated methyl carboxylates 7 and methyl α-chlorocarboxylates 8 as well as from 7c, d and the sulfur ylide 10 (2c, d).The diastereomers are separated by fractionating distillations (2a, b, c, e) or crystallization (2d) on a 100-g to 1-kg scale (d.e. >99percent).Only low yields of 2c are obtained in the reaction of methyl crotonate (7c) with methyl α-chloroacetate (8a), since 7c predominantly dimerizes to afford 12.The diesters 2 are converted into the pure diastereomeric diacids 3, dicarbonyl dichlorides 4, and dihydrazides 5. 3,3-Dimethyl-cis-1,2-cyclopropanedicarboxylic acid (cis-3f) is obtained by trans-->cis isomerization of trans-3f with the help of acetic anhydride and sodium acetate as catalyst.The configurations of 2-6 and 12 are confirmed by 1H NMR spectroscopy.Derivatives of cis-1,2-dimethyl-1,2-cyclopropanedicarboxylic acid tend to form bicyclic products.Thus, the reaction of cis-3e with phosphorus pentachloride yields mainly the cyclic anhydride 6e and only small amounts of the dicarbonyl dichloride cis-4e.Furthermore, the dihydrazide cis-5e slowly cyclizes in the solid state to give the N-aminoimide 13 and hydrazine, a reaction which is fast in solution.Pure 13 is obtained by thermolysis of cis-5e at 60-65 deg C under high vacuum.

CYCLOPROPANATION OF DIMETHYL FUMARATE AND MALEATE WITH GEM-DIHALIDES CATALYZED BY Co(0)- OR Ni(0)-COMPLEX AND ZINC.

The reaction of bis(acetonitrile)bis(diethyl fumarate)cobalt(0) with dibromomethane gave diethyl trans-1,2-cyclopropanedicarboxylate in a 67% yield based on the cobalt complex. Dimethyl cis-1,2-cyclopropanedicarboxylate was obtained in a 52% yield from the reaction of dimethyl maleate with dibromomethane in the presence of acetonitrilebis(dimethyl maleate)nickel(0) accompanied by the formation of the trans-isomer in a 14% yield. The addition of zinc gave cyclopropanes in over 100% yields based on cobalt or nickel. 3-Methyl- and 3,3-dimethyl-1,2-cyclopropanedicarboxylic acid esters were produced by the reaction of dimethyl fumarate or maleate with 1,1-dibromoethane and 2,2-dibromopropane. The yield in the cobalt catalyst system decreases with an increase of substituents of gem-dibromides, while that in the nickel catalyst system does not vary appreciably.