Carbon disulfide, insertion reactions

In equation (34) the ligand-promoted carbonyl-insertion reaction occurs with —90% retention of configuration. Treatment of 22-(R = r-Bu) with bromine in pentane, chloroform, or carbon disulfide gives reaction... 

Considerably less is known about the chemistry of palladium and platinum 1,1-dithio complexes. Of late, there has been only one report that dealt with the synthesis of a large number of palladium dithiocar-bamates 392). Twenty-five yellow palladium dithiocarbamate complexes were obtained by reaction of PdCla with NaR2dtc in methanol solution. Several other reports have appeared in which a few dithiocarbamate complexes of palladium were synthesized. Thus, the novel [Pd (OH)2dtc 2], which is soluble in water, was isolated 393). The synthesis of optically active palladium(II) complexes of AT-alkyl-a-phen-ethyldithiocarbamates, similar to (XXIV), via the reaction between the optically active amine, CS2, and PdCl2, has been described. From ORD and CD spectra, it has been established that the vicinal contribution of a remote, asymmetric carbon center could give rise to optical activity of the d—d transitions of palladium 394). Carbon disulfide has been shown to insert into the Pt-F bond of [PtF(PPh3)3]HF2, and X-ray studies indicated the structure (XXIX). 

Reaction of 768 with one carbon inserting agents, such as formic acid or carbon disulfide, gave (89MI1) 769 and 770, respectively. Methylation of 770 gave 771. 

The free dithiocarboxylic acids can be isolated, but their salts are preferred. In some cases their metal complexes can be prepared directly by insertion of carbon disulfide into metal-carbon bonds. Thus, the reaction of Grignard reagents, RMgX, with CS2, followed by acid treatment gives the dithiocarboxylic acids RCSSH and metal complexes in good yields.311... 

Insertion into metal nitrogen bonds is illustrated by the formation of the anion [(C6F5)2Pd(S2CNIIPh)] in the reaction of [Pd2(C6F5)4(p-NHPh)2]2-with carbon disulfide.362... 

The fact that organosamarium allyl complexes of the type Cp 2Sm(CH2CH=CHR) can arise from the treatment of Cp 2Sm or [Cp 2Sm(/r-H)]2 with a variety of olefin and diene substrates makes samarium chemistry more intriguing. The reaction modes are illustrated in Scheme 18. These allylsamarium complexes 55 react with C02 to afford the carboxylate products 56, which participate in monometallic/bimetallic interconversions (Equation (10)). Carbon disulfide and 0=C=S also insert into carbon-samarium bonds, which form only monometallic species.29... 

Tp " JMgMe, 42 316 [Tp JZnOH complexes, 42 354-359 use in radiocarbon measurement, 3 303 Carbon disulfide complexes, osmium, 37 239 insertion reactions... 

Note also the reactivity of the heteroleptic plumbylene 174 toward carbon disulfide. Treatment of 174 with excess amount of carbon disulfide resulted in a formation of unexpected product, lead(II) bis(aryl trithiocarbonate) (192), as a yellow, air- and moisture-stable solid (Scheme 14.85). The reaction must involve not only the insertion of carbon disulfide into the Pb—S bond, but also the formal insertion of a sulfur atom into the Pb C(Tbt) bond and subsequent insertion of another... 

Carbon disulfide forms complexes in which the metal has a low oxidation state with almost every transition metal. The complexes have been reviewed extensively.1 7,8 Three bonding modes are found end-on via S, if bonded and bridging between two metal atoms. The evidence for these three bonding types is largely spectroscopic and therefore limited. CS2 shows a variety of insertion and disproportionation reactions. 

The readily accessible enamines react with carbon disulfide and sulfur under mild conditions to produce l,2-dithiole-3-thiones (3b) via 3-amino dithioacids (Scheme 24), The nucleophilic character of the enamines is necessary for the initial reaction and to activate the sulfur (from Sg) for further insertion (67AG(E)294). Modified procedures produce other heterocycles. The yields of thiones (3b) may be low but this versatile reaction produces thiones that may be otherwise difficultly accessible, especially by direct sulfurization procedures, e.g. 1-morpholinocyclohexene may be converted into tetrahydrobenzo-1,2-dithiole-3-thione (142) in 40% yield. By contrast, direct sulfurization of 1-methylcyc-lohexene gives benzo-l,2-dithiole-3-thione (77b). Even dihydronaphtho-l,2-dithiole-3-thione (143) may be made by this procedure, although this compound may be dehydrogenated readily by sulfur at 220 °C. 

The silatropic process combined with the addition reaction can be realized with quite a number of compounds, including carbodiimides [Eq. (6a)], isocyanates, carbon disulfide [Eq. (6b)], or carbon dioxide [Eq. (6c)], which exhibit cumulated hetero double bonds. The first step, insertion between the P-Si bond, is followed by a silyl migration (32-35). 

C. Carbon Disulfide and Carbon Diselenide 1. Insertion Reactions... 

---