We report a highly efficient and selective catalytic system, ABNO (9-azabicyclo-[3.3.1]nonane N-oxyl)/HNO3, for the aerobic oxidation of substituted furans to cis-2-ene-1,4-diones under mild reaction conditions using oxygen as the oxidant. The catalyst system is amenable to various substituted (mon-, di-, and tri-) furans and tolerates diverse functional groups, including cyano, nitro, naphthyl, ketone
我们报告了一种高效和选择性催化体系 ABNO (9-azabicyclo-[3.3.1] nonane N -oxyl)/HNO 3,用于将取代的呋喃有氧氧化为顺式-2-ene-1,4-二酮以氧气为氧化剂,反应条件温和。该催化剂体系适用于各种取代的(单-、二-和三-)呋喃,并耐受多种官能团,包括氰基、硝基、萘基、酮、酯、杂环,甚至甲酰基。基于对照和18个O标记实验,提出了氧化的可能机理。
Synthesis of Tetraacetal Pentaoxa-Cages and Convex Oxa-Cages by Ozonolysis of 7-Oxabicyclo[2.2.1]heptenes
作者:Chu-Chung Lin、Hsien-Jen Wu
DOI:10.1055/s-1996-4291
日期:1996.6
Tetraacetal pentaoxa-cage compounds 4a and 4b and convex oxa-cage compounds 6, 7 and 8 are synthesized from alkylfurans in three steps. Ozonolysis of the endo adducts 2a and 2b in dichloromethane at -78°C followed by reduction with dimethyl sulfide gave the tetraacetal pentaoxa-cages 4a and 4b in 85-90% yields, respectively. Ozonolysis of 2a and 2b in dichloromethane at -78°C followed by treatment with triethylamine gave the convex oxa-cages 6, 7 and 8 in 85-90% yields, respectively. The synthesis of the tetraacetal pentaoxa-cage 12, possessing aromatic substituents directly on the skeleton of the oxa-cages, has also been accomplished.
Novel Oxa-Cage Compounds: Synthesis, Structures, and the Formation Mechanism of Tetraacetal Oxa-Cages and Convex Tetraquinane Oxa-Cages
作者:Hsien-Jen Wu、Chu-Chung Lin
DOI:10.1021/jo00128a031
日期:1995.11
Several novel tetraacetal era-cage compounds 5a-d and convex tetraquinane era-cage compounds 16a-d and 17b-d are synthesized from alkylfurans in three steps. Ozonolysis of the cis-endo-1,4-diones 3a-d in dichloromethane at -78 degrees C followed by reduction with dimethyl sulfide gives the era-cages 5a-d in high yields, respectively. The structures of these new tetraacetal era-cages are deduced from their spectral data and proven for the first time by X-ray analysis of the crystalline compound 5a. Ozonolysis of 3a-d in dichloromethane at -78 degrees C followed by treatment with triethylamine gives the convex tetraquinane era-cages 16a-d and 17b-d in 85-90% yields, respectively. The structures of these novel convex tetraquinane era-cages are finally proven by X-ray analysis of the crystalline compound 16a. Two reaction mechanisms via the common final ozonides are proposed for the formation of these two different types of era-cage compounds. The structures of the final ozonides formed by ozonolysis of the norbornene derivatives 3 are deduced to be 9 with endo stereochemistry on the basis of their spectral data and the formation of these two types of era-cages from the final ozonides. In reaction with the final ozonides, triethylamine is found to act as a base instead of a reducing agent, a different function from that of dimethyl sulfide. The synthesis of era-cages 24 and 25, which possess aromatic substituents directly on the skeleton, has also been accomplished.