Hydroxypropyl-side-chains

Studies directed toward the synthesis of bicyclomycin have resulted in the discovery of efficient routes to the construction of the 2-oxa-8,10-diazabicyclo[4.2.2]decane system (160). Thus, the monolactim ether (155) with a hydroxypropyl side chain at position 3, on oxidation with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ), gave the product (156) in good yield, presumably via an iminium species (Scheme 51). No trace of the spiro compound (157) could be detected in this reaction. The formation of (156) is probably kinetically controlled. Prior protection of the alcohol as a silyl ether, followed by DDQ oxidation, gave the pyrazinone (158) subsequent deprotection and acid treatment gave the thermodynamically preferred spiro compound (159). The method has been extended to the synthesis of (160), having an exocyclic methylene this compound is a key intermediate in the total synthesis of bicyclomycin [88JCS(P1)2585]. 

Compounds 142 and 143 could be transformed into a variety of derivatives, such as acetals, oximes, semicarbazones, and hydrazones.154 Other types of monoketone-derived products, especially oxime ethers 144 containing a 3-amino-2-(hydroxypropyl) side-chain, have been synthesized and evaluated as potential drugs216 (see Scheme 39). 

Stereospecific replacement of the p-aminobenzoyl(Glu) by the L-erythro-l,2-di-hydroxypropyl side chain furnishes tetrahydrobiopterin (BPH4, 2) [6]. 

The method was successfully applied to the synthesis of examples of the penitrem class of terpenoid indoles by introducing a 2-(l,l-dimethyl-3-hydroxypropyl) side-chain by using 3,3-dimethylbutyrolactone as the acylating agent (Equation (29)) <89T243l>. 

The plan was to elaborate the pyran moiety throu the aldehyde while the skipped triene would be elaborated through the protected hydroxypropyl side chain. 

Cellulose, a disaccharide of D-glucose, represents the basic molecule, stereo-chemically differing from dextrose in the bonds existing between the two monomers a )S-glycoside bond in cellulose and a a-glycoside bond in dextrose. To increase hydrophilic properties, methoxy- and hydroxypropyl- side-chains are replaced by hydroxy groups (Fig. 22). The molecule is uncharged. 

HPC is synthesized by chemical modification of cellulose with an etherilying agent, propylene oxide that results in the introduction of hydroxypropyl side chains onto... 

The structural resemblance of NCCs and CCs, as well as their comparable SARs, indicate that they bind to CB1 in a similar fashion. The side chain and the phenolic hydroxyl of an NCC are crucial for activity. The hydroxypropyl chain of CP55,940 is not necessary for... 

Note Examples are potassium salts of unbranched alkanoic acids, lecithin, certain polyisocyanates, cellulose derivatives with side-chains, such as (2-hydroxypropyl)cellulose, and cyanobiphenyl derivatives of alkyl(triethyl)ammonium bromide. 

Transmetalation of the vinylmercurial derivative with n-BuLi, followed by reaction with 2-lithium thienylcyanocuprate and subsequent addition of BF3-OEt2 and 167, leads to lactone 168 in 86% yield. Cationic biscyclization of vinylsilane 168 with TiCL and Ti(Oi-Pr)4 (at a proportion of 5 1), followed by the cleavage of the remaining acetal (oxidization of the hydroxypropyl ether side chain and subsequent 15-elimination of piperidinium acetate) leads to secondary alcohol 169. 

Likewise, the secondary hydroxyl group in the hydroxypropyl group can undergo hydroxypropylation to give a side chain ... 

A purified form of cellulose is reacted with sodium hydroxide to produce a swollen alkali cellulose that is chemically more reactive than untreated cellulose. The alkali cellulose is then reacted with propylene oxide at elevated temperature and pressure. The propylene oxide can be substituted on the cellulose through an ether linkage at the three reactive hydroxyls present on each anhydroglucose monomer unit of the cellulose chain. Etherification takes place in such a way that hydroxypropyl substituent groups contain almost entirely secondary hydroxyls. The secondary hydroxyl present in the side chain is available for further reaction with the propylene oxide, and chaining-out may take place. This results in the... 

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