Thioketenes, imines

Raasch, and Schaumann and co-workers, have studied the reactions of bis (trifluoromethyl)thioketene (83 R1 = CF3) with alkenes, with thioketones, and with carbodiimides or Schiff-base imines. The products were, respectively, thietans, 1,3-dithietans (84 R1 = CF3), and 1,3-thiazetidines (85 R1 = CF3) (from the carbodiimide).114,115 With phenyl azide the 1,2,3,4-thiatriazoline (86 R = CF3) is formed subsequent pyrolysis yields2,l-benzisothiazole.114... 

J-NR s 0-Lactam+ P4S10 Imine + thioketene 67JHC619 79CB1000... 

Bis(trifluoromethyl)thioketene reacts with some imines to form 1,3-thiazetidines (78JOC2500). One derivative has been used by Dupont in surface treatment of water-repellent textiles (71USP3592811). 

From carboxylic esters or amides 6-64 Addition of imines to thioketenes (P-thiolactams)... 

Scheme 19 Formation of (3-thiolactams from thioketenes and imines...

Sordo et al. [79] investigated computationally the reaction between thioketenes (79) and imines to yield (3-thiolactams (80) (Scheme 19), a reaction investigated experimentally by Schaumann [80]. 

As illustrated in Fig. 6, imines serve as important intermediates for a number of solid-phase syntheses. Additional uses for these versatile intermediates are described in Fig. 9. Resin-bound thioketene acetals have been shown to condense with imines to provide, after reductive cleavage, a route to substituted aminoalcohols 6 [45], Aminophosphinic acids 7 were prepared by allowing bis(trimethylsilyl)phosphonite to react with resin-bound imines [46],... 

Other thermal 1,3-dipolar cycloadditions are the reactions between nitrile sulfides and electron-deficient aldehydes and ketones forming 1,3,4-oxathiazolines (98 Scheme 19) between aryl thioketones and thiofluorenone 5-tosylimide to yield the 1,3,4-dithiazolidines (204) and between thioketene S-oxides and imines, yielding in one case the 1,2,4-oxathiazolidine (136). 

Thioketenes, for example, 463, add to imines, carbodiimides, and azines to give 1,3-thiazetidines with exocyclic double bonds, as exemplified by the synthesis of 464. A novel ring contraction of 464a gives 1,3-thiazetidine 464b. 1,3-Thiazetidlnes are postulated as intermediates in the photochemical addition of thiobenzophenone to imines. They fragment to the two possible thiocarbonyl components and imines. ... 

RCH=C=0, except when these are generated in situ by decomposition of a diazo ketone (the Wolff rearrangement, 18-8) in the presence of the imine. It has been done with ketene, but the more usual course with this reagent is an addition to the enamine tautomer of the substrate. Thioketenes ° (R2C=C=S) give p-thio-Imines also form p-lactams when treated with (i) zinc (or another... 

Hexafluoroacetone azine gives a /8-lactam with acetyl chloride and triethylamine, and not a criss-cross type of [3 -I- 2] adduct with the keten. Detailed mechanistic studies of the addition of thioketen (21) to imines have been interpreted in terms of orbital-symmetry-controlled formation of the dipolar species (22) rather than a classical zwitterionic intermediate. ... 

The kinds of cumulenes covered with this treatment include allenes, bu-tatrienes, and pentatetraenes on the one side, and ketenes, ketene imines, car-bodiimides, diazocompounds, and thioketenes on the other side. The molecular spectra under consideration include photoelectron (pe), electronic uv absorption spectra, C-, N- ( N-), and H-nmr spectra as well as molar rotations and optical rotatory dispersions (ORD). Molecular properties related to theoretical indices (not observables), such as electron densities, are discussed on a semi-empirical CNDO/S or at initio STO-3G MO level. 

NMR-Chemical Shifts of Ketenes, Ketene Imines, Carbodiimides, Diazocompounds, and Thioketenes... 

All these well-established concepts obviously are useful for the discussion of the planar cumuienes, such as ketenes, diazocompounds, thioketenes, and butatrienes. For nonplanar cumuienes (allenes, ketene imines, carbodiimides, pentatetraenes) the situation is not so simple, as the proper classification of electronic states depends essentially on the substitution patterns of the molecules (lc,24,25,73). The usual concepts based on VB arguments have led toclassiH-cations and analytical descriptions of allenic electronic systems (or orbitals) in terms of two perpendicular, isolated tt systems, especially in terms of two-center ethylenic tt systems (24). Sometimes, hyperconjugation of the eth-ylenic C=C tt system with the CH2 group orbitals of corresponding symmetry has been taken into consideration (24). 

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