Synthesis of Aminopyrazolesfrom α- OxoketeneO,N-Acetals Using MontmorilloniteK-10/Ultrasound

Abstract

5(3)-Amino-3(5) phenylpyrazoles 3a-f have been conveniently prepared by condensation of a-oxoketene O,N-acetals 2a-g with hydrazine using montmorillonite K-10 as solid support under sonication.

Copper‐Catalyzed Aerobic Oxidations of 3‐N‐Hydoxyaminoprop‐1‐ynes to Form 3‐Substituted 3‐Amino‐2‐en‐1‐ones: Oxidative Mannich Reactions with a Skeletal Rearrangement

“…(3)]. Among these products, highly functionalized 2‐en‐1‐ones 3 and 4 were prepared from uncommon and sophisticated reagents including β‐oxothioxo esters,14a α‐oxoketene S , S ‐ketals,14b aryl isothiocyanate,14c 3,5‐disubstituted isoxazole,14d and β‐ketothioamides 14e. In this oxidative skeletal rearrangement, nitrone intermediates II were generated initially and attacked by nucleophiles before proceeding to the products.…”

Efficient Regiocontrolled Synthesis and Antimicrobial Activity of Pyrazoles

“…1 H NMR (400 MHz, CDCl 3 ): d = 7.23-7.86 (m, 10 H), 5.97 (s, 1 H), 4.21 (q, J = 7.0, 2 H), 1.46 (t, J = 7.0, 3 H). 13…”

“…These heterocyclic systems are similar to 5-(chloromethyl)-1H-pyrazole 1 and 5(3)amino-substituted 3(5)-phenyl-1H-pyrazoles 2a-g ( Figure 1) which we have previously prepared. 12,13 The heterocyclic 3-amino-substituted 1,5-diphenylpyrazoles 5a-e (Scheme 1), 3-ethoxy-5-phenyl-1H-pyrazole (6) (Scheme 2) and 5-ethoxy-1,3-diphenyl-1H-pyrazole (7) (Scheme 3) were synthesized and, together with compounds 1 and 2a-g, their antibacterial and antifungal activities were tested. A series of 3-amino-substituted 1,5-diphenylpyrazoles 5a-e was synthesized regioselectively from the cyclization reaction of a-oxoketene O,N-acetals 4a-e with phenylhydrazine on montmorillonite K-10, as solid support under ultrasound (Scheme 1).…”

“…The precursors 4a-e are polarized ketenes representing a new class of versatile functionalized enamine carbonylic compound 14 and were prepared by reported procedures. 13 Scheme 1 Synthesis of the 3-amino-substituted 1,5-diphenylpyrazoles 5a-e…”

The use of benzil to obtain functionalized N-heterocycles

“…1 Our research group has been studying methodologies for the synthesis of heterocyclic systems using the reactions of 1,3-dielectrophiles, such as -oxothioxo--oxoketene-O,N-acetals, ethyl-2-chloro-acetoacetate and -enamino carbonylic and functionalized with a series of dinucleophiles. [2][3][4][5][6] The synthesis of these compounds has been successfully exploited through the methodology of reaction in solid support using montmorillonita, K-10, as a solid support associated to microwave energy or ultrasound sonication. These studies have provided different heterocyclic classes as pyrazoles, isoxazoles, 1,2-diazetine and triazin-3-one.…”