30264-53-0Relevant academic research and scientific papers
SELECTIVE 1,4-DIACETOXYLATION OF CONJUGATED DIENES WITH TELLURIUM(IV) OXIDE
Uemura, Sakae,Fukuzawa, Shin-ichi,Okano, Masaya
, p. 5331 - 5334 (1981)
Oxidation of several linear conjugated dienes with tellurium(IV) oxide and lithium bromide in acetic acid affords an isomeric mixture of the corresponding diacetoxyalkenes (1,2- and 1,4-addition products), 1,4-isomer being highly selectively produced when the ratio of LiBr/TeO2 is 5-10.
Liquid-phase 1,4-Diacetoxylation of Conjugated Dienes with Tellurium(IV) Oxide and Alkali Metal Halides
Uemura, Sakae,Fukuzawa, Shin-ichi,Patil, Suresh R.,Okano, Masaya
, p. 499 - 504 (2007/10/02)
Oxidation of buta-1,3-diene, isoprene, and 2,3-dimethylbuta-1,3-diene with tellurium(IV) oxide and lithium bromide in acetic acid affords an isomeric mixture of the corresponding diacetoxyalkenes (1,2- and 1,4-addition products).The product yield and selectivity for 1,4-isomers are high when an excess of LiBr is employed (LiBr/TeO2 = 5-10).The reaction also proceeds in the presence of NaBr, KBr, LiCl, HBr, or I2 in the place of LiBr, but both the selectivity for 1,4-isomers and the product yield are lower.The reaction hardly occurs using LiF, LiI, NaCl, Br2, and NH4Br as a halogen source.The reaction proceeds catalytically with respect to TeO2 to some extent when a re-oxidant such as H2O2 or t-BuOOH is used.In the cases of 2,5-dimethylhexa-2,4-diene, cyclopenta-1,3-diene, cyclohexa-1,3-diene, and cyclo-octa-1,3-diene the results are unsatisfactory in either the product yield or the selectivity for 1,4-isomers.Halogeno- and/or acetoxy-telluriation of a diene followed by acetolysis of the produced C-X (X = halogen) and C-Te bonds are proposed as one of the possible reaction pathways.
DIACETOXYLATION OF CONJUGATED DIENES WITH THALLIUM(III) ACETATE IN ACETIC ACID
Uemura, Sakae,Miyoshi, Haruo,Tabata, Akira,Okano, Masaya
, p. 291 - 295 (2007/10/02)
The reaction of conjugated dienes such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2,5-dimethyl-2,4-hexadiene, 1,3-cyclopentadiene, and 1,3-cyclohexadiene with thallium(III) acetate in acetic acid at 10-65 deg C for 0.5-15 hr affords an isomeric mixture of the corresponding diacetoxyalkenes (1,2- and 1,4-addition products) in 10-92 percent yields.The 1,2-addition products are predominantly formed in all cases examined except the case of 1,3-cyclopentadiene.The reaction is assumed to proceed through acetoxythallation and dethallation steps, the latter step being accompanied and/or followed by an attack of acetoxyl group.An initial attack of thallium moiety is proposed to occur mainly at C-1 and C-2 carbons in the cases of linear terminal dienes and cyclic dienes, respectively.
