Ditosylates acid esters

IcPs more readily afford bisquaternary salts as compared to IbPs. For example, l,3,5-trialkyl(dialkylphenyl)imidazolio[4,5-c]pyridinium ditosylates 255 and 256 were obtained by fusion with toluene sulphonic acid esters of 1,2-dimethyl- 86 or l-phenyl-2-methyl-IcP 612 (70KG228, 71KG693), or of a mixture of A -monomethyl IcP derivatives (72KG683). 

G>Alkylation with tosylates Gycloalkanedicarboxylic acid esters from ditosylates... 

When the methylenation of D-mannitol is carried out at a higher temperature and for a shorter time, there is produced a dimethylene-D-mannitol (m. p. 204-208°), in addition to the triacetal previously mentioned.68 The dimethylene compound is not oxidized by periodic acid and its ditosyl ester does not exchange with sodium iodide, even in acetic anhydride at 140°.62 Consequently it must be either 1,2,4,6- or 1,3,4,6-dimethylene-D-mannitol (the 1,2,4,6- and 1,3,5,6-structures are identical) the 1,3 4,6-structure was favored by Ness, Hann and Hudson40 in view of the rapidity of its conversion into 1,3 2,5 4,6-trimethylene-D-mannitol. 

DithiomethoxymethyIphenol, 306 Di-p-toluoyl-o-tartrate, 351 Di-p-tolylcarbodiimide, 351-352, 1148 1,1-Di-p-tolylethane, 11, 659 Di-p-tolylthiourea, 351 N,0-Ditosyl-3-aminopropanol, 918 v/c-Ditosylates, 1089 Divinylmercury, 352-353 Docosanedioic add, 438, 708 -Dodecadiene, 1009 Dodecahydrotriphenylene, 991 Dodecane-l,2-dioic acid, 477,788 methyl ester amide, 212 Dodecanol, 958 Dodecanyl tosylate, 958-959... 

Amino-acid Protection. - Carboxyamidomethyl (CAM) esters have been shown to be useful protecting groups in a-chymotrypsin and papain-catalysed peptide hydrolysis and synthesis.5 10 1,3-Dioxans (582) can be obtained from Na-protected serine derivatives by acid-catalysed transacetalation and are sufficiently robust to survive both amino deprotection and peptide coupling reactions. 11 (L)-Histidine benzyl ester can be prepared as the ditosylate salt... 

A/,N -Ditosyl-2,3-naphthalenediamine was reacted with succinoyl chloride in the presence of sodium carbonate to yield the napthodiazocine 75 (84MI1). Thompson reacted 5,6-diamino-1,3-dimethyluracil hydrate with succinic and phthalic anhydrides and obtained 76 and 77, respectively. When succinic anhydride was reacted with 2,3-diaminopyridine, however, only one amino group reacted to give an intermediate diamino acid, which cyclized to 22 (see Section II,A,2) (86JHC1545). Siemion and Wieland condensed homoanthranilic acid derivative 78 with 1-proline p-nitrophenyl ester and... 

The synthesis has been modified to produce a series of porphyrin octaethanol derivatives (ethers) [162]. Pyrrole trimethyl ester (37) is selectively hydrolysed with sodium methoxide in methanol to give the diacid monoester (38), which is reduced (BH3/THF) and tosylated. The ditosylate was heated with the appropriate alcohol to afford the diether (with concommital transesterification of the pyrrolic a-ester). Oxidation with lead tetra-acetate gave compound 39, which was converted to the metal-free porphyrin in one pot by treatment with potassium hydroxide to hydrolyse the ester, hydrobromic acid to decarboxylate and cyclize, and chloranil to oxidize the macrocycle to the porphyrin (Scheme 44). 

Dimethyl-3,4-dipropoxythiophene (ProDOT-Me2) has further increased properties in several respects, but an alternative synthetic strategy had been necessary compared to ProDOT. The synthesis of ProDOT-Me2 was first published in 1999.11 In the same publication, ProDOT synthesis was performed in the manner described before by Williamson ether synthesis with 1,3- dibro-mopropane and 3,4-dihydrox5 iopene-2,5-diethylcarboxylate and subsequent ester hydrolysis and decarboxylation.i For the preparation of the new ProDOT-Me, in principle the same procedure has been used, utilizing 2-methylpropane-l,3-ditosylate instead of the 1,3-dibromide.n In contrast to the less substituted ProDOT or ProDOT-Me, Williamson ether synthesis with neopentylbromide or similar compounds was not sufficient for ProDOT-Me2— not unexpected for a neopentyl structure. So acid catalyzed... 

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