Chemistry of Tetraalkoxyethenes I: Synthesis of 1,1,2,2-Tetraalkoxy-3-cyanocyclobutanes and 5,5,6,6-Tetraalkoxy-3-cyano-4-phenyl-5,6-dihydro-4H-pyranes

N-Sulfonylbenzotriazoles as Advantageous Reagents for C-Sulfonylation

“…Synthesis of α -Cyanoalkyl Sulfones. α-Cyanoalkyl sulfones have extensive synthetic uses, e.g., for the preparation of pyridones, 4-aminopyrimidines, 5,6-dihydro-4 H -pyrans, tetrahydrofurans, cyclobutanes, cyclopropanes, and biologically active compounds such as β -amido sulfones and l -indospicines …”

Properties and reactions of ylidenemalononitriles

“…Presumably, cyclopropanation does not involve dichlorocarbene, but the trichloromethylated derivative 116.2158 A novel, simple cyclopropane synthesis involves the reaction of ylidenemalononitriles, e.g., 28, 81, with nitromethane in the presence of base. 218 (2-Bromo-2-methylpropylidene)malononitrile (117) which is similar to the Favorskii rearrangement, involves an unstable cyclopropane intermediate (121,122). Nucleophilic attack at the 2-position of cyclopropane (121, 122) produces an anion (123,124) which leads to the open acetal (119,120).…”

“…Bulky or electron-releasing substituents at the 2-position in ylidenemalononitriles retard cyclobutane formation. 218 Benzylidenemalononitrile (6) reacts with the enamine 134 to give a 2:1 adduct (135) which can be hydrolyzed to 136. 224 The 1:1 adduct (137) of 6 and 134 is unstable.…”

Cycloadditions of Ketene Diethyl Acetal and 2-Methylene-1,3-dioxepane to Electrophilic Alkenes

“…Thermal reactions of the electron-rich donor alkenes D with electron-poor acceptor alkenes A usually lead to cyclobutanes 2 via intermediate zwitterions 1 , as shown in Scheme . − However, in certain cases cyclohexanes of the types 2A:1D ( 3 , via zwitterion 5 ) and 2D:1A ( 4 , via zwitterion 6 ) resulting from two molecules of one component and one of the other have been reported. Acyclic products from the trapping of zwitterion 1 with water or ethanol, such as 7 , are also sometimes found.…”