Sulfonylurea compounds have the formula ##STR1## in which R is selected from the group consisting of 1-4 carbon alkyl, phenyl, and methyl substituted phenyl; R.sub.1 is selected from the group consisting of hydrogen and 1-4 carbon alkyl; and R.sub.2 is selected from the group consisting of mono- and polyhalosubstituted phenyl, 3-6 carbon alkynyl, and 2-6 carbon alkoxyalkyl.
Alkane- and arenesulfonyl isocyanates were added to benzocyclopropene across the C–C σ-bond of the three-membered ring, giving 2-sulfonyl-1-isoindolinones. The reaction with C,N-diphenylnitrone afforded a similar cyclization product, 3,4-dihydro-3,4-diphenyl-1H-2,3-benzoxazine. These reactions are considered to proceed through zwitterionic intermediates formed by the fission of the C–C σ-bond of the
4-thioxo-2-azetidinones by cycloaddition of thioketenes with isocyanates
作者:Ernst Schaumann、Armin Röhr、Gunadi Adiwidjaja
DOI:10.1016/s0040-4039(00)92874-0
日期:1980.1
The (2+2) cycloaddition of thioketenes with isocyanates yields 4-thioxo-2-azetidinones , which can be hydrolyzed to the N-unsubstituted compound and thus used as versatile intermediates.
The [5 + 2] cycloadditionreaction of 2-vinylaziridines with sulfonylisocyanates proceeded smoothly under mild conditions, and various cyclic ureas were isolated in high yields. The remarkable solvent effect on the reaction was observed, and the preferential formation of the seven-membered ring occurred when the reaction was carried out in CH2Cl2. The scope and limitation were studied, and the mechanism
An iridium-catalyzed C–H allylation of acrylamides with conjugated dienes was developed, using NH-Ts amide as the directing group. The ligand- and additive-free protocol provided a convenient and atom economic synthesis of branched 1,4-diene skeletons, enabling the tolerance of a wide scope of functionalities such as OMe, F, Cl, Br and CF3. The utility of this protocol is also demonstrated by a preparative