A green, economical synthesis of β-ketonitriles and trifunctionalized building blocks from esters and lactones

• Daniel P. Pienaar,
• Kamogelo R. Butsi,
• Amanda L. Rousseau and
• Dean Brady

Beilstein J. Org. Chem. 2019, 15, 2930–2935, doi:10.3762/bjoc.15.287

• solvents was successfully exploited using inexpensive KOt-Bu to obtain a variety of β-ketonitriles and trifunctionalized building blocks, including useful O-unprotected diols. It was discovered that lactones react to produce the corresponding derivatized cyclic hemiketals. Furthermore, the addition of a

• catalytic amount of isopropanol, or 18-crown-6, was necessary to facilitate the reaction and to reduce side-product formation under ambient conditions. Keywords: acylation; β-ketonitrile; enolizable; trifunctionalized; sustainable; Introduction β-Ketonitriles represent highly versatile intermediates for

• environmentally unfriendly transition-metal-based reactions. Acylations of in situ-generated nitrile anions with esters to produce β-ketonitriles were first reported long ago, for example by using sodium methoxide [2], sodium ethoxide [3] or sodium amide [4][5]. The reaction was found to proceed more efficiently

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• β-ketonitriles, arylhydrazines and aryl sulfonyl hydrazides as sulfur source [21]. The chemistry of iodine-catalyzed transformations has emerged as a greener, efficient and economical alternative to transition metals in organic synthesis [22][23][24]. However, the synthesis of selenium-containing 5

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• catalysts like L-proline, InCl3 and ZrCl4 also resulted in the formation of o-hydroxyphenylpyrazolo[3,4-b]pyridine derivatives 85 but no product was formed in iodine- and acetic acid-catalyzed reactions (Scheme 22). Huang et al. [70] investigated a three-component reaction of β-ketonitriles 15, 5

• time for the completion of reaction. El-borai et al. [71] accomplished the synthesis of pyrazolo[3,4-b]pyridine derivatives 88 in which the multicomponent reactions of β-ketonitriles 15, 5-aminopyrazole 16 and anisaldehyde (47) were carried out in acetic acid under conventional heating and microwave

• assistance (Scheme 24). The microwave-assisted reaction provided better yields of pyrazolo[3,4-b]pyridine derivatives 88 as compared to reactions under conventional heating conditions in short time. Hill et al. [72][73] reported the synthesis of pyrazolo[3,4-b]pyridines 89 from the reaction β-ketonitriles 15

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

• involve the reactions of β-ketonitriles, malononitrile, alkylidenemalononitriles and their derivatives with hydrazines, as well as some novel miscellaneous methods. Keywords: alkylidenemalononitriles; 5-aminopyrazoles; hydrazines; β-ketonitriles; malononitriles; Review The 5-aminopyrazole system

• methods have recently appeared. Some of the important methods are outlined below. 1. Reaction of β-ketonitriles with hydrazines The most versatile method available for the synthesis of 5-aminopyrazoles involves the condensation of β-ketonitriles with hydrazines. β-Ketonitriles 1 react smoothly with

• 20 on treatment with 5% HCl in ethanol underwent cyclization to afford 21. A novel solid phase synthesis of some 5-aminopyrazoles 24 and their N-acyl and N-sulfonyl derivatives has recently been reported by Watson et al. [38] via the resin supported β-ketonitriles 22 (Scheme 7). The resin supported