Owing to the greater anisotropism of the g tensor, the ESR signals of thioketyls are broader than those of the ketyls. Coupling of the methyl protons of (1 a ) is therefore not resolved under the given conditions. Assignment of the satellite signals is based upon intensities and comparison with the spectrum of the thioketyl having a natural isotopic abundance. Only thecomponents with mI= fz/' are visible in the quadruplet due to 33Scoupling. A positive sign is deduced for a& from variations in line Our studies on width in the thiocarbonyl I3C (1 b ) yielded a sulfur coupling constant of as% +0.2mT[11; by analogy we assume ( 1 a ) to have us>O. Comparison of the coupling constants a& and in (1 a ) with those in ( 2 ) and in some substituted di-tert-butylmethyl radicals[61shows that the spin population at the thiocarbonyl C atom p; is about 0.8 to 0.9. Hence di-fert-butyl thioketyl resembles an alkyl radical more closely than a thiyl radical. This result confirms an INDO calculation by Ohno et a/.[']. The measured coupling constants can be reproduced by known or plausible 0-7t parameters[']. There is accordingly no need to postulate a pyramidal configuration for ( I ), even as assumed for ketyls[8"l and the tert-butyl though this possibility cannot be entirely ruled out. Received: July 4, 1977 [ Z 790b IE] German version: Angew. Chern. 89, 744 (1977) CAS Registry number: ( I a ) , 63588-77-2 Planned Dissertation by C . P . Klages, Universitit Hamburg. The pertluori has already been reported by G . A. inated species [CF3-CS-CF,] Russell, J . L. Grrlock, G . R . U n d e r ~ . o o dJ., Am. Chem. SOC. 94, 5209 (1 972). C . - P . Klagra, J . h.>.s, Angew. Chem. 89, 743 (1977): Angew. Chem. Int. Ed. Engl. 16. 725 (1977). Generated with potassium in tetrahydrofuran: N . Hirora, S. I . Weissmun, J . Am. Chem. SOC. X2, 4424 (1960). Generated with potassium-sodium alloy in dimethoxyethane: G. A . Russell, G . R. Underwood, J . Phys. Chem. 72, 1074 (1968). N . M. Atkertont Electron Spin Resonance. Wiley, New York 1973, pp. 339ff. D. Griller. K . U . Ingold, J. Am. Chem. Soc. 96, 6715 (1974). A . Ohno, K . Nakamura, M. Uohama. S. Oka, T Yamahe, S. Nagata, Bull. Chem. SOC. Jpn. 48, 3718 (1975). a) G. R. Ufwlrrwood, Mol. Phys. 22, 729 (1971); b) J . B. Lish, L. F . Williams, 0. E . Wood, J . Am. Chem. Soc. 98, 227 (1976): P . J . Krusrc, P . Mrukin, ihid. 98, 228 (1976); however, see also: 7: A. Claxton, E. Plarr, M . C . R . Symons, Mol. Phys. 32, 1321 (1976): and references cited therein. [I]       [S] The structures of the compounds are confirmed by their IR spectra, which show an intense isocyanide absorption at 21 10 and2100cm-'andaC+Nabsorptionat 1632 and 1660cm-', respectively. In the "C-NMR spectrumf2]of ( 2 a ) a signal for the isocyanide group is observed in the expected range at 6 = 169.3. 131 Compared to the N-acyl isocyanides, the N-imidoyl isocyanides are distinctly more stable in dilute solution; thus ( 2 ~ is) transformed into the thermodynamically more stable imidoyl cyanide (3) only in the course of days, ( 2 b ) in several hours. However, if the solutions are concentrated at room temperature or reaction of the imidobromide is carried out in boiling chloroform formation of the imidoyl cyanides (3) Isolation of an N-imidoyl isocyanide in pure form has so far been realized only in the case of the diphenyl derivative ( 2 a ) , which is obtained in 85 % yield in the form of yellow crystals on low-temperature crystallization from petroleum ether. It melts at 60°C and has a weak aromatic isonitrile odor. It can be stored at room temperature for a few days, and at - 20°C indefinitely. O n melting it decomposes, giving mainly (3 a). Hydrolysis with dilute HCI leads to benzanilide in good yields, and reaction with methanol affords mainly N-phenylbenzimino esters. According to mass spectral data the expected trimerization of ( 2 ) , in analogy to the N-acyl isocyanides, does not take place, even under the most varied conditions. In contrast, in the thermal transformation of ( 2 a ) into ( 3 a ) varying amounts (10 to 30 %) of a by-product are observed which could be identified by an authentic synthesis as 2,2'-diphenyl-4,4-bisquinazoline ( 5 a ) . We interpret its formation in terms of an initial head-to-head dimerization of ( 2 a ) to give the heterocumulene ( 4 a), which by double electrocyclic ring closure and subsequent oxidation can elude trimerizati~n[~I. Attempts to transform P-styryl isocyanides into 2,2'-bisisoquinolines in the same way have so far failed. N-Imidoyl Isocyanides [**I By Gerhard Hope and Bernd Lungel*] Successful preparation of the first N-acyl isocyanides from carboxylic acid iodides and silver cyanide[ raised the question whether structurally related isocyanides could be prepared according to the same principle. We have found that the N-phenylimidoyl bromides (1 a ) and ( 1 b ) undergo rapid reaction with silver cyanide in CHCl3 to give the imidoyl isocyanides ( 2 a ) and ( 2 b ) , respectively. -. ~ [*] Priv.-Doz. Dr. G Hone, Dip].-Chem. B. Lange lnstitut fur Organische Chemie der Tecbnischen Universitit Strasse des 17. Juni 135. D-1000 Berlin 12 (Germany) [**] Reactions of Organic Halogen Compounds with Silver Cyanide, Part 4. This work was supported by the Deutsche Forschungsgemeinschaft.Part 3 : [I]. AngeK Chem. Int. Ed Enyl. 16 (1977) No. 10 Experimental Synthesis of ( 2 a ) : 1.34 g (5.15 mmol) N-phenylbenzimidoyl bromide is added to a solution of AgC"'] (1.7 g, 12.7mmol) in anhydrous CHzCIz (20ml). After 10 minutes' stirring at 20°C the silver salt is filtered off and the filtrate evaporated down at 0"C/0. 1 torr. The orange-red residue is extracted several times with petroleum ether. O n cooling the concentrated petroleum extract from 0°C to ca. -60"C, 0.90g (85 %) ( 2 a ) crystallized out, m.p. 60°C. Synthesis of ( 5 a ) : A solution of AgCN (1.34g, 10mmol) and N-phenylbenzimidoyl bromide (1.04 g, 4.0 mmol) in anhydrous benzene (25 ml) is heated under reflux for 4 h. The silver salts are separated by filtration and washed several times with hot benzene. The combined filtrates are concentrated and 727 then treated with petroleum ether. This affords 0.26g (32 %) ( 5 a ) , m.p. 293-294°C. 0.31 g (38%) ( 3 a ) can be obtained from the petroleum ether solution by distillation. Received: July 4. 1977 [Z 789 IE] German version: Angew. Chem. 89, 742 (1977) CAS Registry numbers: ( 1 u), 40168-06-7; (1 b ) , 63588-82-9; ( 2 a ) . 63588-83-0; (Zb), 63588-84-1; ( 3 a ) , 4686-14-0; ( 5 a), 60538-88-7; AgCN, 506-64-9 G. Hojle, B. Lunge. Angew. Chem. 89, 272 (1977); Angew. Chem. Int. Ed. Engl. 16, 262 (1977). Bruker W H 270 at 67.88 MHz in CDCI, at 30°C; 13C enrichment in theisocyanidegroup90%,; halfwidthofsignal l 0 H z a t 6 = 169.3. Oncooling, a coalescence of this signal a t ca. - 10°C is followed at - 50°C by its replacement by two new signals of comparable intensity at 6=146.3 and 157.2, which can be assigned t o the E- and Z-isomers. Unusual, however, is that both signals are shifted t o higher field. The possibility that we observed the dimer ( 4 a ) , likely to be present in the equilibrium, is ruled out by the low-temperature IR spectrum. This thermolability casts doubt upon the isolation  of N-alkylformimidoyl isocyanides in admixture with the corresponding cyanides. The IR and "C-NMR data  (2120 cm-' and Sac= 157.7, resp.) suggest that these compounds are actually alkyl isocyanides originating from basecatalyzed H C N elimination from the N-alkylformimidoyl cyanides. J . H . Boyer, J . Kooi, J. Chem. SOC.Perkin I. 1975, 1743; J . H. Boyer, J . Dunn, J . Kooi, J . Am. Chem. SOC.98, 1099 (1976). A cyanide-catalyzed dimerization of ( 2 a ) by way of a 2-phenylquinazoline can be ruled out since added 2-(m-tolyl)quinazoline i s neither consumed nor incorporated in ( Z a ) . [l]    [S] N-Acyl-N-arylsulfonyldiazenes ; Detection and Use in the Synthesis of Amides By Hansjurgen Golz, Bernd Glatz, Georges Haas, Gunter Helmchen, and Hans Muxfeldt (deceased)[*] While N,N'-diacyldiazenes are in many cases stable and readily accessible, to our knowledge the N,N'-disulfonyl- and N-acyl-N'-sulfonyldiazenes (excepting azobissulfates) have so far not been reported'']. Owing to the pronounced nucleofugal character of the sulfonylazo group['] these compounds ought to represent an interesting new class of acylating agents. We have now been able to demonstrate the existence of a compound of type ( 2 ) , uiz. N-benzoyl-N'-tosyldiazene ( 2 a ) (cf. Scheme 1 and Table 1). Oxidation of the hydrazide ( I a ) with lead tetraacetate in the presence of cyclopentadiene at -78°C leads to formation of the cycloadduct (3)[31in 33 % yield, and on addition of boron trifluoride ether in 53% yieldr41(cf. experimental procedure). In order to estimate the lifetime of ( 2 a ) the temperature and the interval of time between completion of oxidation and addition of cyclopentadiene were varied. Oxidation at - 50°C and addition of cyclopentadiene after 30 minutes leads to 40 % (3), whereas oxidation at -30°C and addition of cyclopentadiene after 10 minutes leads to only traces of (3). Consequently, at temperatures below ca. -50°C ( 2 a ) is sufficiently stable for its isolation. Table 1. Carboxamides ( 4 ) and sulfinamides ( 6 ) prepared (see experimental) from hydrazides ( I ) and benzylamine (R3=CH2C6H5)by oxidation with lead tetraacetate. Reactant R' R' T ["CI Products yield [ %] -60 ( 4 a ) >98 25 -60 25 -80 (4a) -50 25 -60 25 (4b) (46) (4c) (412) (4c) (4c) (4c) 75 77 51 >98 89 28 92 9 - 5 (6a) (6b) 2 (66) 12 ~ (6b) 9 ( 6 6 ) 42 (6c) 5 ( 6 c ) 76 N-Acyl-N'-arylsulfonyldiazenes (2) can acylate amines. Thus, oxidation of the hydrazides ( I a)-( 1 e ) with lead tetraacetate in the presence of benzylamine below -60°C leads to the carboxamides (4)15] in good yields, together with small amounts of the sulfinamides (6) (cf. Table 1 and experimental procedure). The amount of ( 6 ) can reach significant proportions if the reaction is carried out at room temperature. It follows from our present studies and from numerous other data[61that the ratio ( 6 ) / ( 4 ) increases with increasing temperature and increasing bulkiness of R' and R2.Electronic effects have comparatively little influence in this respectL6? The results can be interpreted in terms of Scheme 1. The diazenes ( 2 ) stable at -60°C react cleanly with amines to give carboxamides; however, at higher temperatures competing elimination of nitrogen leads to the mixed anhydrides ( 5 ) . These are preferentially attacked at the sulfur atom by arnines1'1. This is confirmed by predominant formation of the sulfinamide ( 6 e ) from ( I e ) at room temperature; in this instance the situation is especially sterically unfavorable for attack at the sulfur atom. Experimental [**I 2-Benzoyl-3-tos~l-2,3-diaza-S-norbornene (3): A solution of lead tetraacetate (4.0 mmol) in dichloromethane (25 ml) is added dropwise during I h at -78°C to a solution of ( 1 a ) (880mg, 3.03 mmol),cyclopentadiene(30.3mmol), and boron trifluorideether(1.54mmol)in THF/acetonitrile (1/1)(SO ml). After a further 4 h at -78°C the solution is allowed to warm over a period of ca. 20 h to room temperature. The crude product obtained after treatment with ether, extraction with sodium hydrogen carbonate solution, drying (sodium sulfate) and removal of organic phase by evaporation is chromatographed on 300g silica gel (chloroform/acetone 95/5, 15 ml fractions). Fractions 64 to 80 yielded 564mg (53 %) ( 3 ) , colorless crystals, m. p. 148-1 49 "C, after recrystallization from ethyl acetate/ hexane. Carboxamides ( 4 ) : A solution of lead tetraacetate (1 mmol) in dichloromethane (10ml) is added dropwise during 20min to a solution of hydrazide ( I ) (1 mmol) and benzylamine (Smmol) in T H F (for temperature see Table 1). After 2 h 728 Angew. Chem. Jnt. Ed. Engl. 16 (1977) N o . 10 [*] Dr. H. Golz, Dr. B. Glatz, Dr. G. Helmchen ['I, Prof. Dr. H. Muxfeldt ['I (deceased) Institut fur Organische Chemie, Biochemie und lsotopenforschung der Universitat Pfaffenwaldring 55, D-7000 Stuttgart 80 (Germany) Dr. G. Haas ["'I Ciba-Geigy AG CH-4000 Basel (Switzerland) Author to whom correspondence should be addressed Formerly at Cornell University, Ithaca, N. Y.