Carbodiimides chloro- from

A useful method for the synthesis of 5-chloro-l,2,4-thiadiazoles (206) is the reaction of amidines with trichloromethylsulfenyl chloride (see Equation (30)). 3-Halo derivatives (349) (X = Cl, Br, I) (Equation (57)) have been obtained in moderate yields from the corresponding amines (348) via the Sandmeyer-Gatterman reaction <84CHEC-I(6)463>. 3-Chloro-l,2,4-thiadiazolin-5-ones (350) and (351) can be prepared by reacting chlorocarbonylsulfenyl chloride with carbodiimides or cyanamides respectively (Scheme 79) <84CHEC-I(6)463>. 

Chloro-l-methylpyridinium iodide (683) functions as an important mediator in a variety of different reactions. Esters are formed in high yield from acids and alcohols when reacted with one equivalent of (683) in the presence of two equivalents of triethylamine (Scheme 158) (75CL1045). cv-Hydroxy acids are lactonized under similar conditions (76CL49). The pyridinium salt (683) will also convert thioureas into carbodiimides (77CL575) and pyridine-2-thiones to pyridyl sulfides (75CL1159). 

C-(w-propyl)-N-phenylnitrone to N-phenylmaleimide, 46, 96 semicarbazide hydrochloride to ami-noacetone hydrochloride, 45,1 tetraphenylcyclopentadienone to diphenyl acetylene, 46, 44 Alcohols, synthesis of equatorial, 47, 19 Aldehydes, aromatic, synthesis of, 47,1 /8-chloro-og3-unsaturated, from ketones and dimethylformamide-phosphorus oxychloride, 46, 20 from alkyl halides, 47, 97 from oxidation of alcohols with dimethyl sulfoxide, dicyclohexyl carbodiimide, and pyridinium trifluoroacetate, 47, 27 Alkylation, of 2-carbomethoxycyclo-pentanone with benzyl chloride, 45, 7... 

Alkyl-5-aryliminothiatriazolines (21) do not produce carbodiimides but give rise to benzothiazoles (22) when heated in toluene at 120-130 °C for several hours (equation 9). With the 3-chloro compound, two isomeric benzothiazoles are formed resulting from attack... 

The same carbodiimide is obtained from cyanamide and bis(diisopropylamino)chloro-phosphane in the presence of triethylamine (85% yield), and from the N-cyano-P-hydrogenoiminophosphoraneMe3SnCl adduct andbis(diisopropylamino)chlorophosphane (95 % yield). 

Fig. 2.100. Mechanism proposed for the reaction of the [Rh(Tp )(CNneopentyl)] fragment, obtained photochemically from the carbodiimide complex, with chloro-substituted alkanes.

However, the chloro derivative [2]C1 (R = Cl) can be more conveniently prepared from the readily accessible bis(trimethylsilyl) carbodiimide 38 by condensation with SC12 at 50°C (83CB416). The instability of SF2 has prevented analogous formation of FCNSSN+. 

A carbodiimide-related reagent is 2-chloro-l,3-dimethylimidazolinium chloride (CDC). It can act as a powerful dehydrating agent, equivalent to DCC. Nitriles 1379 can be prepared from primary amides 1377 or aldoximes 1380 on several structures at room temperature within reaction times of 4-72 h and in yields of 64-99% [1137]. As a strong electrophile, CDC reacts with 0-nucleophiles to form 1506,... 

The iminophosphoranes (63), that are readily synthesized from 2-chloro-5-cyano-6-ethoxy-4-phenylpyridine-3-carboxaldehyde, were reacted with aromatic isocyanates to obtain directly several new 1,8-naphthyridines in an aza-Wittig/electrocyclic ring-closure process." Phosphazene (64) was reacted with phenyl isocyanate (or 4-chlorophenyl isocyanate) to give a carbodiimide which was cyclized to afford a series of new, 2-substituted 3-aryl-8,9,10,ll-tetrahydro-5-methyl[l]benzothieno[3,2 5,6]-pyrido[4,3-d]pyrimidin-4(3//)-ones." ... 

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