Stereoselective Aza Diels−Alder Reaction on Solid Phase:  A Facile Synthesis of Hexahydrocinnoline Derivatives

Abstract

As part of our continuing studies of polymer-supported pericyclic reactions for preparing biologically interesting heterocyclic compounds, we have introduced a traceless solid-phase synthesis of hexahydrocinnolines. We developed a method in which mild reaction conditions can be used for the hetero-Diels-Alder reactions on a polymeric support. The dienoic 3-vinyl-2-cyclohexenol attached to a Wang resin through an ether linkage undergoes [4 + 2] cycloaddition reaction with several azadienophiles. The highly stereoselective Diels-Alder reaction showed preferential formation of a single cycloadduct resulting from an anti attack of the dienophile on the polymer-bound diene. Trifluoroacetic acid-mediated cleavage of the polymer-bound cycloadducts yields fused nonaromatic hexahydrocinnolines in moderate yields in three steps.

Studies of Cobalt Particle Size Effects on Fischer–Tropsch Synthesis over Core–Shell‐Structured Catalysts

“…The bright orange crude product was purified by silica gel flash column chromatography (ethyl acetate/hexane, 1:20 to 1:10) to give diene 5 (3.97 g, 91 %) as a pale yellow liquid. The characterization data were in agreement with those reported 12b…”

Sulfamic Acid as Versatile Green Catalyst Used For Synthetic Organic Chemistry: A Comprehensive Update

“…An interesting class is heterocycles containing urazole [1,2,4-triazolidine-3,5-diones] derivatives which received attention due to their clinical and catalytic activity. [54][55] In pursuit of efficient, cost-effective and greener approaches for the synthesis of N-containing heterocycles, Kidwai and Chauhan [56] employed a multicomponent reaction protocol for the synthesis of triazolo[1,2-a]indazolones using SA (Scheme 16). SA was obviously superior to other catalysts, giving a yield of 82 % by using 10 mol.% of the catalyst.…”

“…Nitrogen‐containing heterocycles are of significant importance as they exist in natural products and exhibit biological activity in a range of pharmaceutical products. An interesting class is heterocycles containing urazole [1,2,4‐triazolidine‐3,5‐diones] derivatives which received attention due to their clinical and catalytic activity [54–55] . In pursuit of efficient, cost‐effective and greener approaches for the synthesis of N ‐containing heterocycles, Kidwai and Chauhan [56] employed a multicomponent reaction protocol for the synthesis of triazolo[1,2‐a]indazolones using SA (Scheme 16).…”

Cinnoline Scaffold—A Molecular Heart of Medicinal Chemistry?

“…Synthesis of cinnoline and its derivatives has been extensively discussed in many papers [2,3,4,5,6,7,8,9]. Until 2011, no compounds containing the cinnoline ring system were found in nature.…”