- Catalytic asymmetric tamura cycloadditions
-
In the presence of a novel, tert-butyl-substituted squaramide-based catalyst, enolizable anhydrides react with alkylidene oxindoles to generate spirooxindole products of significant synthetic interest with excellent enantio- and diastereocontrol. The methodology is of wide scope and encompasses both homophthalic and glutaconic anhydride derivatives, which lead to structurally diverse products. Glutaconic acid-derived anhydrides undergo a clean post-cyclization decarboxylation process which is not a feature of reactions involving homophthalic acid-derived anhydrides. The unusual influence of reaction temperature on diastereocontrol has been probed, with reactions occurring at 30 °C and -30 °C delivering products epimeric at one stereocenter only, in near optical purity. Squared away: The first strategy for bringing about enantioselective Tamura reactions is reported. In the presence of a squaramide-based catalyst, enolizable anhydrides react with alkylidene oxindoles to generate spirooxindole products with excellent enantio- and diastereocontrol. The methodology is of wide scope and leads to structurally diverse products.
- Manoni, Francesco,Connon, Stephen J.
-
p. 2628 - 2632
(2014/03/21)
-
- Regioselective Acetylation of some N-Methylpyrrole Derivatives with Isopropenyl Acetate and Different Acetic Anhydrides
-
We studied the reactions of some N-methylpyrrole derivatives with isopropenyl acetate and different acetic anhydrides.We have found that the reaction with isopropenyl acetate afforded 5-acetylpyrrole derivatives while with acetic anhydrides acetylation oc
- Gizur, Tibor,Harsanyi, Kalman
-
p. 361 - 366
(2007/10/02)
-
- Facile and Efficient Syntheses of Carboxylic Anhydrides and Amides Using (Trimethylsilyl)ethoxyacetylene
-
(Trimethylsilyl)ethoxyacetylene, a stable and easy-handling reagent, serves as an excellent dehydrating agent for the synthesis of carboxylic anhydrides and amides from the corresponding carboxylic acids.By means of this reagent, various types of acid-sensitive carboxylic anhydrides and amides were obtained almost in quantative yields.Twenty-two examples of carboxylic anhydrides and 12 examples of amides were presented.
- Kita, Yasuyuki,Akai, Shuji,Ajimura, Naomi,Yoshigi, Mayumi,Tsugoshi, Teruhisa,et al.
-
p. 4150 - 4158
(2007/10/02)
-
- A MILD AND FACILE SYNTHESIS OF CARBOXYLIC ANHYDRIDES
-
Reaction of carboxylic acids with trimethylsilylethoxyacetylene in an inert solvent under mild conditions affords the corresponding carboxylic anhydrides in almost quantitative yields.
- Kita, Y.,Akai, S.,Yoshigi, M.,Nakajima, Y.,Yasuda, H.,Tamura, Y.
-
p. 6027 - 6030
(2007/10/02)
-