Group 13 sulfides hydrazine

The chloromethylpyrimido[5,4-( ]-l,2,4-triazine 86 is an extremely versatile starting material (see Section 10.20.7.2, Equation 12) and was synthesized from the commercially available thiol 151 as shown in Scheme 25. Thus, 6 -methylation of compound 151 gave the sulfide 152, which was nitrosated to allow access to the nitroso-thiomethyl derivative 153. Nucleophilic substitution of the thiomethyl group by hydrazine gave the cyclization precursor 154, which underwent cyclization with chloroacetaldehyde diethyl acetal under acidic conditions to give the chloro-methylpyrimido[5,4-( ]-l,2,4-triazine 86 after workup with aqueous ammonia <2003BML2895>. 

Pyran-thiones, when treated with hydrazine, can give pyridazines, l-amino-4(l//)-pyridinethiones, or pyrazoles. Pyridazines are the exclusive or main product when the starting pyranthiones are substituted at position 3 with a hydroxy group. Perhaps hydrazine attacks position 6, followed by elimination of hydrogen sulfide to give 51 (78BCJI79). 

If, on the other hand, a nitro group must be reduced to an amino group without reducing the sulfidic bond, hydrazine is the reagent of choice [683]. 

The reduction of carbazole nitro groups to the primary amines is straightforward stannous chloride, tin-hydrochloric acid, iron-hydrochloric acid" hydrogen-palladium/charcoal," hydrogen-nickel,hydrazine-palladium,and hydrazine-nickeP have all been employed. 3,6-Dichloro-l,8-dinitrocarbazole was partially reduced with sodium hydrogen sulfide to give l-amino-8-nitro-3,6-dichloro-carbazole. ... 

A halogen directly attached to the 1,2,4-triazine ring is very reactive and can be replaced by most other nucleophiles as outlined in Scheme 9. Tlie reactivity toward neutral nucleophiles decreases from the 5-position to the 3- and 6-positions, while that towards anionic nucleophiles decreases from the 5-position to the 6- and 3-positions. Among nucleophiles which displace halogen atoms are water, alcohols, amines, hydrazine, hydroxyl-amine, thiols and hydrogen sulfide. It is also reported that the bromine in 6-bromo-1,2,4-triazine-3,5-dione can be replaced by fluorine (323) or by a cyano group (324). 

Phthalimide protection is stable towards acids and bases, but can be cleaved with strong nucleophiles, such as hydrazines or sulfides, or by reduction with sodium boro-hydride [230]. More sensitive towards nucleophilic attack than unsubstituted phthalimide is tetrachlorophthalimide [33]. This group has been successfully used as N(a) protection of amino acids in the solid-phase synthesis of peptides (deprotection N2H4/DMF (15 85), 40 °C, 1 h coupling DIC/HOAt/amino acid (1 1 1), 3 equiv. of each, DMF, 25 °C, 4 h [294]). Typical conditions for the removal of phthaloyl protection on cross-linked polystyrene include treatment of the resin with hydrazine hydrate [295,296], with methyl hydrazine [297], or with primary aliphatic amines [298] in DMF, EtOH, or solvent mixtures for several hours at room temperature or above [296,299,300]. Illustrative examples are sketched in Figure 10.15. It has been claimed that the hydrazinolysis of polystyrene-bound phthalimides proceeds more readily in DCM or DCE than in DMF [301]. 

N-f-butoxycarbonyl group (e.g., 25% HBr-HOAc, TFA-anisole), but is removed by TFA in the presence of dimethyl sulfide within 40-60 minutes at 23°. The N -tosyl protecting group is also removed under these conditions, but at a slower rate. The p-methoxysulfonyl group is also removed by N-hydroxybenzotriazole or by 1 Af NaOH within 1 hour, but only partially by 80% hydrazine hydrate after 24 hours. 

Heteroatomic nucleophiles which also have been shown to undergo addition across the 3,4-double bond of quinazolines 5 and with which the addition products 6 were isolated include the methoxide anionand sodium hydrogen sulfite.(For addition of sodium hydrogen sulfite and hydrazine at the 4-position of quinazoline 3-oxides with concomitant deoxygenation of the A(-oxide group, cf p 105.) Equilibrium and rate constants have been determined at 25 °C for the covalent addition of water, the bisulfite ion, hydroxylamine, urea, 2-sulfanylethanol, and hydrogen sulfide to the 3,4-bond of the quinazoline cation. ... 

The reduction of aryl alkyl tellurium dihalides in which the alkyl group bears an electronegative substituent (chlorine, oxygen) on the )S-carbon, cleaves the alkyl group and forms diaryl ditellurium compounds. Sodium sulfide " , sodium hydrogen sulfite, hydrazine sulfate, and zinc effect this conversion. 

Termination for name of certain monoatomic anions chloride, sulfide Termination for names of the more electronegative constituent [atom or group] in binary type names disulfiir dichloride triiodide cyanide Termination for trivial name of certain hydrides such as N2H4 and PHj hydrazine, phosphine... 

IJC(B)109>. A mechanistic rationale (Scheme 6), which involves initial attack by hydrazine at the thiocarbonyl group followed by intramolecular nucleophilic attack at the ring sulfur by the terminal nitrogen of the hydrazine so formed accompanied by loss of hydrogen sulfide, is proposed. Attack by hydrazine at the ester carbonyl centre is discounted as the methyl and ethyl esters (37 R = Me or Et) yield different products, both of which show the appropriate alkyl resonances in... 

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