Elemental Sulfur-Promoted Oxidative Rearranging Coupling between o-Aminophenols and Ketones: A Synthesis of 2-Alkyl benzoxazoles under Mild Conditions
作者:Thanh Binh Nguyen、Pascal Retailleau
DOI:10.1021/acs.orglett.7b01775
日期:2017.7.21
In the presence of N-methylpiperidine, elemental sulfur was found to act as excellent oxidant in promoting oxidative rearranging coupling between o-aminophenols and ketones. A wide range of 2-alkylbenzoxazoles was obtained under mild conditions.
A transition‐metal‐free approach to the alkylation/arylation of benzoxazole was developed by employing Tf2O‐activated‐amide as the alkylating/arylating reagent. The mild reaction conditions, and particularly insensitivity to air and water, further enhance the synthetic potential in pharmaceutical synthesis.
A copper‐catalyzed amination of arylhalides with nitriles has been developed. The use of nitriles as nitrogen nucleophiles can make the synthesis of N‐arylamides more simple than that using amides through in‐situ hydrolysis. A variety of N‐arylamides and benzoxazole derivatives can be synthesized according to this approach.
Carbon−Carbon Bond Cleavage of Diynes through the Hydroamination with Transition Metal Catalysts
作者:Tomohiro Shimada、Yoshinori Yamamoto
DOI:10.1021/ja034105o
日期:2003.6.1
The C-Cbondcleavage of terminal and internal diynes takes place readily in the presence of catalytic amounts of Ru3(CO)12 or Pd(NO3)2 and of 2-aminophenol, giving the corresponding benzoxazoles and ketones in good to high yields. There are two different modes of the bondcleavage: (a) an alkyne C-C triple bond is cleaved, and (b) the C-C single bond between the two alkyne groups is cleaved.
在催化量的 Ru3(CO)12 或 Pd(NO3)2 和 2-氨基苯酚存在下,末端和内部二炔的 CC 键断裂很容易发生,从而以良好或高产率得到相应的苯并恶唑和酮。有两种不同的键断裂模式:(a) 炔烃 CC 三键断裂,和 (b) 两个炔基之间的 CC 单键断裂。
Facile and Efficient Synthesis of Benzoxazoles and Benzimidazoles: The Application of Hantzsch Ester 1,4-Dihydropyridines in Reductive Cyclization Reactions
Both benzoxazole and benzimidazole are common heterocyclic scaffolds in biologically active and medicinally significant compounds. Reductivecyclization of ortho-substituted nitrobenzene derivatives provides an attractive route to benzoxazole or benzimidazole ring formation. Unfortunately, only a few synthetic methods by reductivecyclization of ortho-nitro compounds have been reported and the yields