Y-Propiolactone

Propagation according to scheme (168a) is typical of carbocation initiators both modes were observed with acylium (RC+=0) initiators. During chain growth from y -propiolactone, the concentracion of acylium ions decreases until oxonium ions become the active centres. In e-caprolactone polymerization, both types of centre continue to operate. 

A soln. of 3 hydroxy-2,2,4-trimethyl-valeric acid in chloroform stirred with isobutyryl chloride for 1 hr. at 0-10° and 2 hrs. at room temp. -> a,a-dimethyl-/ -isopropyl-y -propiolactone. Y 81.4%. Also with other reagents... 

Figure 10.1 Polymers from y-Propiolactone and 6-Valerolactone (8) Table 10.5 Properties of Biodegradable...

A mixture of a-chloro-a-deoxykojic acid, y -propiolactone, and trifluoroacetic acid refluxed 1 hr. 2-chloromethyl-5-hydroxy-6-(j -hydroxypropionyl)-4-... 

Stability of 4-membered heterocyclics. A soln. of a-phenyl-a-n-propyl-)( -amino-propionic acid in 25%-acetic acid added at 0-5° during 0.5 hr. to aq. NaNOg, stirring continued 1.5 hrs. at 0° a-phenyl-a-n-propyl-y -propiolactone. Y 78%.—4-membered heterocyclics are stabilized by disubstitution in position 3. F. e. s. E. Testa et al., A. 619, 47 (1958) cf. Synth. Meth. 15, 206. 

A recent example of the initiation method involves the living anionic polymerization of y-propiolactone initiated by potassium methacrylate in which the potassium cation is complexed with dibenzo-18-crown-6 (DB18C6) (equation 14). Because the growing chain end is a car-boxylate anion, no side reactions occur at the initiator s double bond. 

Indoles can also be alkylated by lactones[l4]. Base-catalysed reactions have been reported for (3-propiolactone[15], y-butyrolactone[10] and 5-valerolac-tone[10]. These reactions probably reflect the thermodynamic instability of the N -acylindole intermediate which would be formed by attack at the carbonyl group relative to reclosure to the lactone. The reversibility of the JV-acylation would permit the thermodynamically favourable N-alkylation to occur. 

P-Hydroxy acids lose water, especially in the presence of an acid catalyst, to give a,P-unsaturated acids, and frequendy P,y-unsaturated acids. P-Hydroxy acids do not form lactones readily because of the difficulty of four-membered ring formation. The simplest P-lactone, P-propiolactone, can be made from ketene and formaldehyde in the presence of methyl borate but not from P-hydroxypropionic acid. P-Propiolactone [57-57-8] is a usehil intermediate for organic synthesis but caution should be exercised when handling this lactone because it is a known carcinogen. 

Reaction with Lactones. Hydroxycarboxyhc acid ester complexes of titanium are formed by reaction of a tetraalkyl titanate with a lactone, such as P-propiolactone, y-butyrolactone, or valerolactone (35). For example. 

Lithium aluminum hydride in ether readily reduces /3-propiolactones to 1,3-diols in fair to good yield. A recent application of this reaction is with the y-bromo-/3-lactone in equation (61), in which reductive cleavage of the bromine atom occurred simultaneously (78CC961). 

Hemminki, K. (1981) Reactions of P-propiolactone, p-butyrolactone and y-butyrolactone with nucleic acids. Chem.-biol. Interact., 34, 323-331... 

The monomers that have been used for the synthesis include glycolide, lactide, (3-propiolactone, (3-butyro lactone, y-butyrolactone, 6-valerolactone, e-caprol-actone, l,5-dioxepan-2-one, pivalolactone, l,4-dioxane-2-one, 2-methylene-1, 3-dioxolane, 2-methylene-l, 3-dioxepane, etc. The structures of some of these monomers are given in Table 1. 

In the reactions of /1-propiolactone, y-valerolactone, and d-valerolactone no products could be isolated due to tarring,Lactides react with sulfur tetrafluoride, without ring opening, to give tetrafluorodioxanes and higher fluorinated dioxanes." 6-Chloro-4-hydroxycoumarin dimerizes upon reaction with sulfur tetrafluoride/hydrogen fluoride to a fluorinated spiro compound. - ... 

Yamashita, M., Takemoto, Y, lhara, E., and Yasuda, H. (1996) Organolanthanide-initiated living polymerizations of e-caprolactone, 8-valerolactone and f -propiolactone. Macromolecules, 29, 1798-1806. 

Related Reagents. iV-Benzyloxycarbonyl-L-serine p-Lactone a,3-Butenolide -y-Butyrolactone Dihydro-5-(hydroxymethyl)-2(3//)-furanone p-Ethynyl-p-propiolactone 3-Propiolactone. 

Without conjugation of the olefmic double bond to the alkoxycarbonyl function, high selectivity and high reactivity are attained in some cyclic systems. Even ester function can be replaced with ether. Thus, (S)-BINAP-Ru-catalyzed high-pressure hydrogenation of four- and five-membered cyclic lactones or carbonates having an exocyclic methylene bond gives (R)-/3-methyl-/3-propiolactone in 92% e.e., (R)-y-methyl-y-butyrolactone in 95% e.e. [35], and the carbonate of (R)-3-methyl-2,3-buta-... 

Koketsu, J., Kojima, S., and Ishii, Y., Reactions between P-propiolactone and dialkyl dimethylphos-phoramidite. Ambident character of P-propiolactone and of dialkyl dimethylphosphoramidite. Bull. Chem. Soc. Jpn., 43, 3232, 1970. 

Svirkin, Y. Y., Xu, J., Gross, R. A., Kaplan, D. L., and Swift, G., Enzyme-catalyzed stereoelective ring-opening polymerization of a-methyl-P-propiolactone, Macromolecules, 29, 4591 597, 1996. 

Since then, research has focused on variables that include enzyme used, substrate selectivity and reaction conditions. Examples of published work looking at one or more of these variable includes the following studies with different monomer substrates co-dodecanolactone (DDL) [34,72,73], co-pentadecanolactone (PDL) [73-77], 3-propiolactone [78, 79], 8-octanolide (8-OL) [80], undecanolactone (UDL) [34, 72, 73, 75, 81], hexadecanolactone (HDL) [72], y-butyrolactone [78], and others (see also Table 4.2). 

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