Ketene mercaptals

Ketene Acetals, Ketene Mercaptals, and Ketene Aminals... 

Ketene mercaptals (27) have rather high C=C barriers (Table 5), and only those with quite strongly electron-accepting groups fall within the region accessible to the DNMR method (45-49). As an example, the C=C barrier for 27... 

Triafulvene compounds (41) with acceptor groups for X and Y have been studied notably by Eicher et al. (55,56), who found C=C barriers from 14 kcal/mol upward (Table 9). The barrier-lowering effect of the acceptor groups seems to fall in the same order as for ketene mercaptals and aminals, but the capacity of the cyclopropenium ring to stabilize the transition state seems to be less than that of the (MeS)2C group in ketene mercaptals. The barrier is quite sensitive... 

Attempts have been made to correlate the effects of acceptor groups on the C=C barriers by Hammett substituent constants. Since the important interaction is concerned with the delocalization of a negative charge, the cr scale should be more appropriate than the normal a scale (136). However, in the ctp scale, CN is more efficient than COMe, which is contrary to experience, and therefore Shvo et al. preferred the ctr = ctp - o, scale (78 see also Sect. II-C-5). Similarly, in a series of ketene mercaptals, a reasonable correlation was found... 

The dialkylation of the ketene mercaptal (311) with chloroacetone afforded (312) in 25% yield. Ketene mercaptal (311) was obtained readily by the action of carbon disulfide on... 

Reaction of 2-aminopyridine and the ketene mercaptals (92) in the presence of sodium ethoxide gave the 2-methylthio derivatives (93).161,162 2-Amino-pyridine and 2-phenyl-4-ethoxymethylene-5-oxazole gave the condensation product 94, which in the presence of sodium ethoxide at room temperature isomerized to 3-benzamido-4-oxo-4H-pyrtdo[l,2-< /]pyrimidine.163... 

Ketene mercaptals 213 (X = CN, COOMe Y = OMe R1 = Me, benzyl) react with 5,5-dialkysulfur diimides (Scheme 20) [R2 = Me, Et, (CH2)2] to give colorless lA.6,2,6-thiadiazines 214. With MeCCl=C-(COOEt)2, the same diimides yield thiadiazines 215 (86CB1745). 

Reaction of 2-aminopyridine and the ketene mercaptals (92) in the presence of sodium ethoxide gave the 2-methylthio derivatives 2-Amino-... 

Without additional reagents Rearrangement of ketene mercaptals... 

A mixture of crude ketene mercaptal or pure allenic dithioester, which can be obtained from the former by heating 15 min. at 100-120° in a neutral distillation... 

Thiolic acid esters from ketene mercaptals C C(SR)g > CHC(0)SR... 

S-Isopropyl-S-phenyl-N-tosylsulfilimine and a 5 mole excess of K-tert-butoxidc in benzene allowed to stand 15 hrs. at room temp, under isopropenyl phenyl sulfide. Y 80%. F. e. s. N. Furukawa, S. Oae, and T. Masuda, Chem. Ind. 1975, 396 with KOH in ert-butanol, prepn. of ketene mercaptals, s. H, Yoshida, T. Ogata, and S. Inokawa, Synthesis 1976, 552. 

Enedisulfides Ene-14-(Uthiols Ketene mercaptal monosulfonium salts - mercaptals... 

Ketene mercaptals from carboxylic acid chlorides... 

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