L Lactone

Carpentier J-F (2010) Discrete metal catalysts for stereoselective rmg-openmg polymerization of chiral racemic [l-lactones. Macromol Rapid Commun 31 1696-1705... 

N.A. Anemone hepatica (DC.) Ker-Gawl. A. patens L. A. pulsutilla L. Lactone protoanemonin (anemonin), triterpenoid saponins, tannins, volatile oil." For cramps, menstrual problems, distress, spasmodic pain of the reproductive system. 

The process of racemization has a number of practical application in the laboratory and in industry. Thus, in the synthesis of an optical isomer it is frequently possible to racemize the unwanted isomer and to separate additional quantities of the desired isomer. By repeating this process a number of times it is theoretically possible to approach a 100% yield of Synthetic product consisting of only one optical isomer, An example of the utilization of such a process is found in the production of pantothenic acid and its salts, In this process the mixture of D- and L-2-hydroxy-3,3-butyrolactones are separated. The D-lactone is condensed with the salt of beta-alanine to give the biologically active salt of pantothenic acid, The remaining L-lactone is racemized and recycled. 

C. Vogel, B. Liebelt, W. Steffan, and H. Kristen, Synthesis, crystal structure, and some reactions of 2,3,4-tri-0-acetyl-/l-D-galactopyranurono-6,l-lactone, J. Carhohydr. Chem., 11 (1992) 287-303. 

Of the catalysts evaluated, those effective for the polymerisation of l>-lactones with ring opening by C(0)-0 bond cleavage [scheme (9)], as well as for the polymerisation of 8- and e-lactones (also with C(0)-0 bond cleavage), have... 

Macrolactonization with inversion,l Lactonization of the optically active seco-acid 1 with P(C6H5)3 and DEAD followed by hydrolysis of the acetonide group gives the cyclic dilactone colletodiol (2), formed with inversion of configuration at the hydroxyl-bearing carbon. Lactonization of 1 with 2,4,6-trichlorobenzoyl chloride and triethylamine (9,478-479) furnishes 6-epicolletodiol after deprotection. 

The reactions of propiolaotone with thioglycoVio aoid, or albumins, of the l lactone of 3-hydroxy butyric acid with coenzyme A and of the -lactone of 2,2- iiphenylhydraciylio acid with various thiols have been doscrihed. 

Taber, D. F., Nakajima, K., Xu, M., Rheingold, A. L. Lactone-Directed Intramolecular Diels-Alder Cyclization Synthesis of trans-Dihydroconfertifolin. J. Org. Chem. 2002, 67, 4501 504. 

Pantenoic acid is used as a vitamine B2 complex, d- and L-pantolactone are used as chiral intermediates in chemical synthesis. The enantioselective hydrolysis is carried out in the aqueous phase with a substrate concentration of 2.69 M = 350 g L 1 (Fig. 19-17). For the synthesis whole cells are immobilized in calcium alginate beads and used in a fixed bed reactor. The immobilized cells retain more than 90 % of their initial activity after 180 days of continuous use. At the end of the reaction l-pantolactone is extracted and reracemized to d,L-pantolactone, which is recycled to the reactor. The D-pantenoic acid is chemically lactonized to D-pantolactone and extracted. By applying cells from Brevibacterium protophormia the L-lactone is available. The biotransformation eliminates several steps that are necessary in the chemical resolution process (Fig. 19-18). 

A more reactive analog of the lactone 1, (5S)-5-[(15,2/ ,55)-menthyloxy]-4-phenylsulfonyl-2(5//)-furanone, has been introduced55. Its cycloaddition to cyclopentadiene is complete in 0.5 hours at room temperature (benzene as solvent) producing the respective adduct in quantitative yield and d.r. [(25, 27 )/(27 ,3S7 )]>99 l. Lactone 1 has been applied to the asymmetric synthesis of (-)-isopodophyllotoxin56. 

Sodium cyanoborohydride. 14. 28 Reduction of cyclic imines. 1 cyclic amines by reduction have apf the reducing agent is the possible pr synthesis of perhydro-l,2-oxazincs Macrolactone formation. [Pg.330]

C15H20O10 l,4,6-Tri-0-acetyl-3-0-(D-l-carboxyethyl)-j -D-glucopyran-ose-2,l -lactone (ACEGLL) ... 

Me glycoside See Methyl glucopyranosi-duronic acid, M-192 Benzyl glycoside See Benzyl glucopyra-nosiduronic add, B-17 6 ->7 Lactone, tri-Ac 2,3,4-Tri-O-acetyl-fS-D-glucopyranurono-6,l-lactone C12H14O9 302.237... 

Figure 4. Plots of reaction temperature versus % e.e. of recovered (l )-lactone in Novozym-435 catalyzed resolution of lactones 1 (A), 2 ( ) and 3 ( )at 23,40 and 60 Ca...

Lactones of type I have bands at 1790-1777 and 1765-1740 cm L Lactones of type II have bands at 1775-1740 and 1740-1715 cm ... 

Pyrolysis kinetics have been carried out on poly-L-lactone salts using TGA linked to various methods such as NMR spectroscopy, gas chromatography and pyrolysis-gas chromatography-mass spectrometry to identify volatile decomposition products. The effect of the end structures on pyrolysis kinetics was examined and the mechanisms of pyrolytic degradation for both polymers identified. 

The delactoniziiig enzyme converts the lactone to ketoadipic acid. It is specific for the (-l-)-lactone. No cofactor requirement was discovered. The reaction sequence is shown in Eq. (26). 

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