Tosylates synthesis

The benzylidene derivative above is used, if both hydroxyl groups on C-2 and C-3 are needed in synthesis. This r/vzns-2,3-diol can be converted to the sterically more hindered a-cpoxide by tosylation of both hydroxy groups and subsequent treatment with base (N.R. Williams, 1970 J.G. Buchanan, 1976). An oxide anion is formed and displaces the sulfonyloxy group by a rearside attack. The oxirane may then be re-opened with nucleophiles, e.g. methyl lithium, and the less hindered carbon atom will react selectively. In the following sequence starting with an a-glucoside only the 2-methyl-2-deoxyaltrose is obtained (S. Hanessian, 1977). 

An alternative strategy is to put a 3-(-2-dioxolanyl)ethanoyl substituent in place first and then add the C7-substituent by a Grignard addition. This approach was applied to the synthesis of 8.2C but in this case it was found necessary to remove the tosyl protecting group prior to cyclization[l]. 

HydrophobicaHy Modified, Ethoxylated Urethane. HEUR associative thickeners are in effect poly(oxyethylene) polymers that contain terminal hydrophobe units (66). They can be synthesized via esterification with monoacids, tosylation reactions, or direct reaction with monoisocyanates. There are problems associated with aH of the methods of synthesis. The general commercial procedure for their synthesis is by a step-growth addition of... 

One of the more important approaches to 1-azirines involves a similar base-induced cycloelimination reaction of a suitably functionalized ketone derivative (route c. Scheme 1). This reaction is analogous to route (b) (Scheme 1) used for the synthesis of aziridines wherein displacement of the leaving group at nitrogen is initiated by a -carbanionic center. An example of this cycloelimination involves the Neber rearrangement of oxime tosylate esters (357 X = OTs) to 1-azirines and subsequently to a-aminoketones (358) (71AHC-(13)45). The reaction has been demonstrated to be configurationally indiscriminate both syn and anti ketoxime tosylate esters afforded the same product mixture of a-aminoketones... 

H-Azepine, 2-methyl-1-methoxycarbonyl-rearrangement, 7, 504 1 //-Azepine, 3-methyl-1 -methoxycarbonyl-cycloaddition reactions, 7, 520 IH-Azepine, 1-phenyl-synthesis, 7, 542 1 H-Azepine, N-phthalimido-formation, 7, 508 IH-Azepine, N-sulfonyl-UV spectra, 7, 501 1 H-Azepine, tetrahydromethylene-synthesis, 7, 540 IH-Azepine, N-p-tosyl-protonation, 7, 509 synthesis, 7, 537 3H-Azepine, 3-acyl-2-alkoxy-synthesis, 7, 542-543 3H-Azepine, 3-acyl-2-methoxy-rearrangements, 7, 505 3H-Azepine, 2-alkoxy-hydrolysis, 7, 510... 

Pyrido[2,3-(i]pyrimidine, 6-cyano-O-tosylation, 3, 211 Pyrido[2,3-(i]pyrimidine, 3,4-dihydro-synthesis, 3, 217... 

Synthesis of the title compound is representative of a number of syntheses of nonaromatic nitrogen heterocycles via Pd(Ill-catalyzed amination of olefins. These tosylated enamines are not readily available by standard synthetic methods, and show potential for further functionalization of the heterocycle. The saturated amine can be synthesized from the title compound by hydrogenation of the double bond followed by photolytic deprotection. ... 

At the same time, Dale and Kristiansen reported a successful synthesis of 18-crown-6 from the diol and ditosylate just as shown in Eq. (3.2), but using benzene as solvent. They obtained the product as its potassium tosylate complex (mp 164°) in 33% yield. The free macrocycle was liberated by chromatography over a column of alumina, eluting with a benzene-cliloroform mixture. Dale and Kristiansen note that the cyclic ether cannot be liberated from its complex by simple heating . ... 

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