Chiral glycerol derivatives

Figure 10. Preparation of chiral glycerol derivatives and D- and L-glycerol acetonide. a 1. Hj/Pd-C 2. methyl isopropenyl ether/pyridinium p-toluensulfonate 3. K2C03/Me0H...

Since the synthesis of glycolipids involves the synthesis of both the lipid and the oligosaccharide portions, we shall also discuss that part of the recorded lipid synthetic work which has involved the use of carbohydrates. In fact, some of the first-recorded applications of carbohydrate molecules as chiral templates are to be found in the lipid field particularly with the use of 1,2 5,6-di-O-isopropylidene-D-mannitol [33] as a precursor of chiral glycerol derivatives for the synthesis of phospholipids and glycolipids based on glycerol and with the use of glucosamine derivatives for the synthesis of phytosphingosines [34] and since this area has not previously been reviewed, it will be treated with a more historical perspective. 

Wang, Y.-F., and Wong, C.-H. 1988. Fipase-catalyzed irreversible transesterification for preparative synthesis of chiral glycerol derivatives./. Org. Chem.,53, 3127-3129. 

Lactones, stereoselective synthesis from chiral glycerol derivatives 82YGK1037. 

The chiral glycerol derivative 355 was prepared by lipase-catalyzed asymmetric /ran5-esterification. Tosylation of 355 followed by hydrolysis gave 356. Hydrogenolysis of 356 gave 3-tosyloxy-l,2-propanediol (357). After... 

The synthetic utihty of the above transformations stems from the fact that many monoesters obtained as a result of hydrolysis may be converted to pharmaceutically important intermediates. For example, the optically active glycerol derivative (27) is a key intermediate in the production of P-blockers. Akyl derivative (25) may be converted into (5)-paraconic acid [4694-66-0] ((5)-5-oxo-3-tetrahydrofurancarboxyhc acid) that is a starting material for the synthesis of (3R)-A-factor. The unsaturated chiral cycHc monoacetate (31) is an optically active synthon for prostaglandins, and the monoester (29) is used for the synthesis of platelet activating factor (PAF) antagonists. 

C-chiral racemic y-hydroxy sulfides were also resolved using PEL under kinetic resolution conditions. The products were transformed into optically active 3-(alkanesulfonyloxy)thiolane salts (Scheme 1). Similarly, 1,2-cyclic sulfite glycerol derivatives cis and trans) were resolved into enantiomers via a Pseudomonas cepacia-catalysed acylation with vinyl butyrate. The E values depended on the solvent used and varied from 2 to 26. ... 

Oriyama subsequently showed that this catalyst system was also effective for the KR of various classes of iec-alcohols, notably P-halohydrins [188] and also certain a-chiral primary alcohols such as glycerol derivatives [184], A solid-supported version of Oriyama s catalyst developed by Janda was found to which induce comparable levels of selectivity [185-187],... 

Cyclic PAF analogues, such as the chiral tetrahydropyrans 361 and 363, represent con-formationally restricted glycerol derivatives that exhibit potent PAF antagonistic activity [126]. A twelve-step sequence converts 349 or 353 to (2i ,3 S)-(360) (ee = 98.8%) or (2S,3R)-2-triphenylmethoxymethyltetrahydropyran-3-ol (362) ( = 96.8%), respectively. These are then appropriately transformed to the corresponding PAF products 361 and 363 [127]. 

In addition, a chiral 1,2-diamine derived from L-proUne was investigated as a catalyst for the KR of primary alcohols with acyl chlorides by Oriyama et al. [50], providing the highest selectivity factors of up to 16 in the case of glycerol derivatives as substrates. Chiral Ph-BOX-Cu(II) complex 17 has also been successfully... 

Laakso, P and Christie, WW (1990) Chromatographic resolution of chiral diacylglycerol derivatives potential in the stereospecific analysis of triacyl-jw-glycerols. Lipids, 25,... 

Already mentioned earlier in this book (see above), raspailynes constitute a series of glycerol enolic ethers, the long-chain enolic part of which is conjugated with an ene-yne system. These unstable derivatives were isolated from the species Raspailia pumila and Raspailia ramosa harvested in Brittany (Bay of Morlaix). There are three series of raspailynes which differ in the stereochemistry of the two double bonds Z,Z (the most common type), Z,E and E,Z (the least common type). In each type the absolute configuration of carbon 2 of glycerol is S, as with all chiral glycerol monoethers encountered so far in marine... 

Enzymatic reduction of carbonyl compounds and enzymatic enantioselective transformation of racemic or meso alcohols (25,43.) are two methodologies that have proven to be beneficial in the preparation of optically active hydroxyl compounds, key chiral building blocks used in carbohydrate and natural product syntheses (44-45. Our interest in this area is to develop enzymatic routes to optically active glycerol and furan derivatives, and hydroxyaldehydes. 

Two isomers of chirally deuterated glycerol have been synthesized from a common boronic ester intermediate 1 (synthesis Section I.I.2.1.3.I.)71. (15,25)-Glycerol-l-fi results if the carbon to which the label is attached is derived from dibromomethane and incorporated into an a-bromo boronic ester intermediate 2, which is then reduced with potassium triisopropoxyborodeuteride to the (1 / ,2/ )-l-deutero boronic ester 3. The synthesis of (lS,25)-glycerol-l- / is completed efficiently by dcboronation with hydrogen peroxide and debenzylation with hydrogen over palladium. 

These ether lipids are all chiral molecules with an R configuration but are derivatives of the nonchiral glycerol. The carbon atoms of glycerol are numbered using the stereochemical system which is described on p. 470. The ether linkage is to the sn-1 carbon atom. Most phospholipids are derivatives of the sn-3 phosphate ester of glycerol. 

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