- Dehydrogenation of Nitrogen Heterocycles Using Graphene Oxide as a Versatile Metal-Free Catalyst under Air
-
Graphene oxide (GO) has been developed as an inexpensive, environmental friendly, metal-free carbocatalyst for the dehydrogenation of nitrogen heterocycles. Valuable compounds, such as quinoline, 3,4-dihydroisoquinoline, quinazoline, and indole derivatives, have been successfully used as substrates. The investigation of various oxygen-containing molecules with different conjugated systems indicated that both the oxygen-containing groups and large π-conjugated system in GO sheets are essential for this reaction. (Figure presented.).
- Zhang, Jingyu,Chen, Shiya,Chen, Fangfang,Xu, Wensheng,Deng, Guo-Jun,Gong, Hang
-
p. 2358 - 2363
(2017/07/22)
-
- Synthesis and catalytic reactivity of D4-symmetric dinorbornabenzene-derived metallotetraarylporphyrins
-
The condensation of the resolved C2-symmetric benzaldehyde, 1,2,3,4,5,6,7,8-octahydro-1:4,5: 8-dimethanoanthracene-9-carboxyaldehyde, with pyrrole produced the first chiral tetraarylporphyrin 1 exhibiting D4-symmetry. The resolved benzaldehyde was synthesized in seven steps from p-benzoquinone and cyclopentadiene and included a resolution via diastereomeric ketals. A manganese chloride complex of porphyrin 1 was used as a catalyst for the asymmetric epoxidation of aromatic substituted alkenes in the presence of excess sodium hypochlorite in up to 7,200 turnovers and up to 76% e.e and >90% yield.
- Halterman, Ronald L.,Jan, Shyi-Tai,Nimmons, Heather L.,Standlee, David J.,Khan, Masood A.
-
p. 11257 - 11276
(2007/10/03)
-
- Enantioselective Synthesis of the (+)-anti-7,8-Dihydrodiol-9,10-epoxide of the Potent Carcinogen Benzopyrene
-
The title compound, the most important genotoxic metabolite of benzopyrene, has been prepared efficiently in a synthesis which capitalized on Jacobsen-type enantioselective epoxidation of 9,10-dihydrodibenzopyrene, cleavage of the epoxide by KOH-Me2SO to give the tetrahydro-trans-7,8-diol, and formation of the dibenzoate from which the contaminating antipode was removed by crystallization.
- Huang, Xiaoming,Harris, Thomas M.
-
p. 1699 - 1700
(2007/10/02)
-
- Enantioselective synthesis of the tumorigenic anti-diol epoxide metabolites of benzo[a]pyrene
-
Efficient, highly enantioselective syntheses of (+) and (-)-anti-benzo[a]pyrene diol epoxide (BPDE) from 9,10-dihydrobenzo[a]pyrene are described. Initial epoxidation catalyzed by (salen) Mn(III) complex gives 7,8-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (
- Harvey, Ronald G.
-
p. 2737 - 2740
(2007/10/02)
-
- Improved Formal Preparation of Enantiomerically Pure anti-Benzopyrene Diol Epoxide.
-
We report an improved, economical formal route to enantiomerically pure anti-benzopyrene diol epoxide (BPDE).A trimethylaluminum catalyzed regio- and stereoselective opening of racemic 7,8-epoxy-7,8,9,10-tetrahydrobenzopyrene with Mosher's acid delivers benzylic esters exclusively.This step is a significant improvement over the lack of regioselectivity of standard procedures.We also show that modification of the subsequent chemical steps further shortens the preparation of enantiomerically pure anti-BPDE.
- Negrete, George R.,Meehan, Thomas
-
p. 4727 - 4730
(2007/10/02)
-
- 1a,11b-Dihydrobenzanthrazirine. A non K-Region Polycylic Arene Imine
-
The synthesis of the title compound is described.Benzanthracene 8,9-oxide (6) was reacted with sodium azide in aqueous acetone and the trans-9-azido-8,9-dihydrobenzanthr-8-ol (7), so formed, was cyclized by tri-n-butylphosphine.Attempts to dehydroge
- Blum. Jochanan,Ben-Shoshan, Shoshanna
-
p. 1461 - 1464
(2007/10/02)
-
- (+)- and (-)-Benzopyrene 7,8-Oxide: Synthesis, Absolute Stereochemistry, and Stereochemical Correlation with Other Mammalian Metabolites of Benzopyrene
-
Optically pure samples of (+)- and (-)-benzopyrene 7,8-oxide have been synthesized from the separated diastereisomers of trans-8-bromo-7-menthyloxyacetoxy-7,8,9,10-tetrahydrobenzopyrene.The latter separation was effected by short-column chromatography-recrystallisation or high pressure chromatography.The absolute stereochemistry of (+)-trans-8-bromo-7-menthyloxyacetoxy-7,8,9,10-tetrahydrobenzopyrene has been assigned as (7S,8S) by an X-ray crystal structure analysis; this structure has in turn been unequivocally correlated with the stereochemistry of (7S,8R)-(-)-benzopyrene 7,8-oxide and a range of mammalian metabolites.
- Boyd, Derek R.,Gadaginamath, Guru S.,Kher, Anil,Malone, John F.,Yagi, Haruhiko,Jerina, Donald M.
-
p. 2112 - 2116
(2007/10/02)
-