application as components of polyurethane resins and plant protecting agents. Owing to the drastic conditions, expensive catalysts, and sometimes inadequate selectivities the best methods of isocyanate synthesis remain those based on the phosgenation of amines.
In the course of searching for new possibilities concerning the synthesis of arylsulfonyl isocyanates, we have discovered that sodium and potassium salts of aromatic N-chlorosulfonamidates (1) can be catalytically carbonylated to arylsulfonyl isocyanates (2) at 20-100°C and a CO pressure of 20-50 bar in CH,Cl, or 1,2-dichIoroethane as solvent [Eq. (a), M = Na, K] . Suitable catalysts are palladium salts and complexes like [PdCI,(CH,CN),], [PdCI,(PhCN),J, [PdCl,(Ph,As),] and [Pd,(dba),] (dba = dibenzylideneace-Pd-catalyst [ArylSO,NCI]M + C O ArylS0,NCO + MCI (a) l a -e 2 a -e tone). The starting compounds l a -e are listed in
Table 1 together with typical yields of the product isocyanates 2a-e. The latter were identified by the strong N = C = 0 stretching Table 1. Yields of arylsulfonyl isocyanates 2 by catalytic carbonylation of Nchlorodrylsulfonamidates @(CO) = 40 bar; solvent CH,CI,). Right-hand column: molecular masses of the corresponding arylsulfonylureds 3 determined by FAB-MS. 1 Aryl a Phenyl a Phenyl b 4-Methylphenyl b 4-Methylphenyl c 2-Chlorophenyl d 2-Bromophenyl e 2-Naphthyl T Catalyst/Additive Yield (Me + H) " CI Of2 [%] O f 3 20 [PdC1,(Ph3As),] 76 31 1 20 PdCI,/CH,CN 71 311 55 [Pd,(dba),] 80 325 20 [PdCI,(PhCN),]/CH,CN 72 325 80 PdCI,/CH,CN 72 389 20 [PdCI,(PhCN),]/CH,CN 76 361 20 PdCI,/CH,CN 76 345 Cooperative Interactions in Molecular Recognition-the Binding of Diamines to a Tetracarboxylic Acid ** By Frank Ebmeyer and Julius Rebek, Jr.* One of the paradigms of molecular recognition studies that have emerged over recent years is the concept of preorganization. It is generally agreed that binding selectivity and [