149302-75-0Relevant articles and documents
Efficient synthesis and hydrolysis of cyclic oxalate esters of glycols.
Itaya, Taisuke,Iida, Takehiko,Gomyo, Yasuko,Natsutani, Itaru,Ohba, Masashi
, p. 346 - 353 (2002)
Based on the mechanism postulated for the formation of the cyclic carbonates 3 in the reactions of glycols 1 with oxalyl chloride in the presence of triethylamine, we present here three efficient syntheses of the cyclic oxalates 2 of various glycols 1 by controlling the formation of 3: replacement of the base by pyridine markedly diminishes yields of 3 in all reactions, realizing dramatic reversals of the product ratios in the reactions with the (R*,R*)-compounds 1g-i,q,r and pinacol (1k); although considerable amounts of the oxalate polymers are formed in the reactions with some (R*,S*)-glycols, this drawback can be removed by the use of 2,4,6-collidine instead of pyridine; 1,1'-oxalyldiimidazole is useful for the synthesis of two selected cyclic oxalates 2e,f. The cyclic oxalates 2 other than trisubstituted and tetrasubstituted ones were found to be very reactive: kinetic studies on the hydrolysis of 1,4-dioxane-2,3-dione (2a) as well as its mono- and some selected 5,6-disubstituted derivatives 2 have revealed that they undergo hydrolysis 260-1500 times more rapidly than diethyl oxalate (12) in acetate buffer-acetonitrile (pH 5.69) at 25 degrees C. Although the cyclic oxalate 21 from cis-1,2-cyclopentanediol (11) was 1.5 times more reactive than 2a, it has been shown with other substrates that increasing number of the alkyl substituents decreases the rate of hydrolysis. On the contrary, the phenyl group was found to have somewhat accelerative effect.
Synthesis of the Cyclic Oxalates of 1,2-Glycols by Controlling the Formation of the Cyclic Carbonates
Itaya, Taisuke,Iida, Takehiko
, p. 1671 - 1672 (2007/10/02)
Cyclic oxalates 2 have been efficiently synthesized by the reaction of 1,2-glycols 1 with oxalyl chloride in the presence of pyridine or 2,4,6-trimethylpyridine, rather than triethylamine, or by reaction with 1,1'-oxalyldiimidazole.
Cyclocondensation of oxalyl chloride with 1,2-glycols
Iida,Itaya
, p. 10511 - 10530 (2007/10/02)
Oxalyl chloride reacts with a wide range of acyclic 1,2-glycols 1 in the presence of triethylamine to produce 1,3-dioxolan-2-ones 3 together with 1,4-dioxane-2,3-diones 2. Ethylene glycol (1d), monosubstituted ethylene glycols 1e, j-l, and erythro-1,2-disubstituted ethylene glycols 1f, m, o provide the cyclic carbonates 3 as the minor products, while the threo-compounds 1g, i, n, p, q and pinacol (1h) afford 3 as the main products. The formation of 3 may be rationalized in terms of stereoelectronically controlled cleavage of the conjugate base 17- of the tetrahedral intermediates. The rate of the conformational change of 17- into 18- and the equilibrium constant between these conformers are proposed to be the major factors affecting the reaction pattern.
Formation of cyclic carbonates in the reactions of 1,2-glycols with oxalyl chloride
Itaya,Iida,Eguchi
, p. 408 - 410 (2007/10/02)
Oxalyl chloride reacts with a wide range of 1,2-glycols in the presence of triethylamine to produce 1,3-dioxolan-2-ones together with 1,4-dioxane-2,3-diones; the ratio of the products largely depends on the structure of the 1,2-glycol. The formation of the cyclic carbonates may be rationalized in terms of stereoelectronically controlled cleavage of the tetrahedral intermediates.
