Reaction with Oxygen and Sulfur Nucleophiles

4-Dloxy-1-metalla-1,3-butadienes and 3-Oxy-1-metalla-1,2,3-butatrienes by Alcoholysis 

Substitution of the alkoxy substituent of a (l-alkynyl)carbene complex 1 has been briefly mentioned for only one case, in which the methoxy 

13C NMR Shifts (8 Values) and IR Frequencies (cm-1, Hexane) of Selected Alkoxy(2-oxyethenyl)carbene Complexes (CO)sM = C(OEt)CH = C(OR)R1 

C(OMe) —CH3 with an ortho ester 175 (iii) the condensation of aryl- or alkylcarbene complexes with enolizable acid amides RCH2 —CONR2, a reaction involving insertion of the C—CN unit of the acid amide into the M=C bond 176 (iv) the insertion of an alkyne into the M=C bond of an (alkoxy)carbene complex 36,177 174 and (v) the base-catalyzed addition of an alcohol to a (l-alkynyl)carbene complex.96 168173 The last reaction has 

The [(2-alkoxy)ethenyl]carbene complexes are obtained as E/Z mixtures, in which the (E)-stereoisomers predominate. Other carbene complexes, in which carbohydrates are bonded directly to the metal center178 or to the carbene carbon atom,179180 are also known. 

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B. Reactions with Oxygen and Sulfur Nucleophiles 1. Hydrolysis... 

Not all nucleophilic displacement reactions require lightly substituted onium ion catalysts for activity. For alkylation of 2-naphthoxide ion with benzyl bromide (Eq. (6)) 40-100% RS, 2% CL polystyrene catalysts 15 and 16 work well54). A 51 % RS catalyst 11 gave good yields in reactions of anionic oxygen and sulfur nucleophiles with alkyl halides 91). 

Displacement Reactions with Carbon, Oxygen, and Sulfur Nucleophiles... 

Appel salt 20 is sensitive to attack of nitrogen, oxygen, and sulfur nucleophiles, especially at the 5-carbon, to form corresponding 5-imines 56, ketone, thione 41, and 5-ylidenes (i.e., 42) which can participate in further reactions with nucleophiles at the same carbon atom with extrusion of diatomic sulfur (S2) and chloride anion. This chemistry started in 1985 when Appel salt was discovered, and is extensively studied at the present time. 

Nucleophilic displacement of the chlorine atom of 3-chloro-1,2-benzisothiazole has proved to be a popular procedure. Boeshagen and Geiger34 have continued their earlier work on nitrogen nucleophiles, and now include carbon, oxygen, and sulfur nucleophiles.35 In some cases, rearrangements occur, as in the formation of 3-amino-2-acylbenzo[6]thiophenes (20) from reaction of 21 with methyl ketones. Similar results are obtained from the reaction of other carbon nucleophiles, and it has been suggested that attack may be either at the 3-carbon or the sulfur atom.36 The reaction of 3-chloro-1,2-benzisothiazole (8) with the anion of ethyl cyanoacetate, for example,... 

The imino-chloride character of 3-chloro-l,5-diphenyl-U, 2,4-thiadiazine 1-oxide (139) has been exploited and displacements of the halogen by oxygen and sulfur nucleophiles, and by hydrazine, to give 3-alkoxy-, 3-alkyIthio-, and 3-hydrazino- (140) 12 ,2,4-thiadiazine 1-oxides have been carried out. On the basis of PMR spectroscopic evidence the product from the reaction with sodium hydrogen sulfide appears to be the 3(4 -thione (141) rather than the tautomeric 3-thiol (Scheme 17) <90JCS(P1)447>. 

Effect of Some Nitrogen-, Oxygen-, and Sulfur-Containing Groups on the Rate Constants for the Reaction of Chloro-s-triazine Derivatives with Various Nucleophiles... 

Sulfur compounds " are better nucleophiles than their oxygen analogs (p. 439), so in most cases these reactions take place faster and more smoothly than the corresponding reactions with oxygen nucleophiles. There is evidence that some of these reactions take place by SET mechanisms. ... 

Thiocarbamate (tc, RHNCSO-) is a monodentate ambidentate ligand, and both oxygen- and sulfur-bonded forms are known for the simple pentaamminecobalt(III) complexes. These undergo redox reactions with chromium(II) ion in water via attack at the remote O or S atom of the S- and O-bound isomers respectively, with a structural trans effect suggested to direct the facile electron transfer in the former.1045 A cobalt-promoted synthesis utilizing the residual nucleophilicity of the coordinated hydroxide in [Co(NH3)5(OH)]2+ in reaction with MeNCS in (MeO)3PO solvent leads to the O-bonded monothiocarbamate, which isomerizes by an intramolecular mechanism to the S-bound isomer in water.1046... 

The lack of reactivity of 3-halo substituents under non-radical nucleophilic substitution conditions allows differential functionalization of pyri-dines by 3-umpolung and 2-nucIeophilic substitution processes. Thus, treatment of 2-fluoro-3-iodopyridine (189) with oxygen or amine nucleophiles affords products 191 which, upon subjection of SRN1 reactions with carbon, phosphorus, and sulfur systems, give 2,3-difunctionalized pyri-dines 192 (Scheme 56) (88JOC2740). 

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