3- Propiolactone synthesis

The carbonylation of COD PdCl2 complex in aqueous sodium acetate produces /rui7x-2-hydroxy-5-cyclooctenecarboxylic acid /i-lactone (240). The lactone is obtained in 79% yield directly by the carbonylation of the COD complex in aqueous sodium acetate solution[220]. /i-Propiolactone (241) is obtained in 72% yield by the reaction of the PdCC complex of ethylene with CO and water in MeCN at —20 " C. /3-Propiolactone synthesis can be carried out with a catalytic amount of PdCC and a stoichiometric amount of CuCl2[221]. 

Finally chloropivalic acid obtained by K. E. Moller from methallyl chloride is of interest as intermediate in the a,a-dimethyl-p-propiolactone synthesis. This lactone shows promise as a monomer for polyester fibers. Studies for polymerization of a,a-dimethyl-p-propiolactone are under way at several companies (Shell, Eastman, Kodak, ICI, Montecatini [424, 432, 510, 794, 795]). 

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. 

A 1992 patent describes the carbonylation of EO to yield /3-propiolactone using a mixture of Co2(CO)8 and 3-hydroxypyridine.982 A recent re-investigation of this system has indicated that the major product is the alternating copolymer, a polyester, catalyzed by the [Co(CO)4] anion (Scheme 24).983 The synthesis of lactones via this methodology has successfully been achieved using Lewis acidic counter-cations (Scheme 25) 984,985 a similar strategy allows /3-lactams to be... 

Liu X-Q, Wang M-X, Li Z-C, Li F-M (1999) Synthesis and ring-opening polymerization of a-chloromethyl-a-methyl-P-propiolactone. Macromol Chem Phys 200 468 73... 

The reaction of several a-amino acid esters with 0-lactones in chloroform solution gave hydroxyamide esters (equation 50), said to be useful fungicides (74JAP(K)74127918>. Enamines derived from cyclohexanone react smoothly with 0-propiolactone to give 3-(2-cyclo-hexanonyl)propionamides in reasonable yields (equation 51). No acylation of the enamine is observed. This reaction has been used as a key step in a new synthesis of 8-aza steroids (75JOC50). Cyclohexanone imines react in the same manner, except that the expected initial product cyclizes to give bicyclic lactams and enaminones (equation 52) (80T3047). 

Diketene also is widely employed as a natural and synthetic fiber cross-linking agent, wood preservative and paper-sizing agent. Both it and /3-propiolactone have wide application as chemical intermediates. The synthetic applications of diketene for the synthesis of aromatic, heterocyclic and aliphatic compounds is exceptionally extensive (74ACR265). 

The reaction has been extended to a synthesis of terpenes from / -methyl-/S-propiolactone, available by hydrogenation of ketene dimer.9 Example ... 

When /J-ethynyl-j8-propiolactone (I) is the substrate, allenic 3,4-alkadienoic acids (2) are obtained in high yield. The reaction has been used for a synthesis of pcllitorine (3). 

Diones are normally synthesized from /3-hydroxy acids in two steps first, conversion into carbamates by reaction with sodium cyanate, and then cyclization with thionyl chloride (Scheme 103) (54JCS839). Alternative preparations utilize oxetanes, which may be combined either with isocyanates in the presence of boron trifluoride (68JAP6808278) or with S-alkylthioureas (Scheme 104) (69ZOR1844). In the last example the initial products are imines (224) which may readily be hydrolyzed to the required diones. Similar methods can be applied to the synthesis of tetrahydro-l,3-thiazine-2,4-diones, and, for instance, the 4-oxo-2-thioxo derivative (225) is obtained from /3-propiolactone and dithiocarbamic acid (Scheme 105) (48JA1001). 

Exaltolide. The key step in a new synthesis of exaltolidc (4) is the three-carbon homologation of a Grignard reagent (1) with /i-propiolactone (2) catalyzed by Cul. The product (3) is converted into 4 in two steps.1... 

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. 

T7177>. Ring-opening polymerization can proceed by two mechanisms depending on the initiator used the coordination-insertion mechanism or the anionic mechanism. While most studies focused on the synthesis of poly(/3-hydroxy butyrate), alternative PHAs were synthesized from a-methyl-/3-pentyl-/3-propiolactone... 

Methyl-3-propiolactone is useful as a four-carbon building block for terpenoid synthesis (eq 4). Citronellic acid (9) isprepared by reaction with the homoprenyl Grignard reagent pulegone (10), citronellol (11), geraniol, and nerol (12) can be obtained by further functional group manipulations. ... 

Alkynylepoxides [123,142,143 Eq. (68) 142] and alkynyl propiolactones [Eq. (69) 144] afforded allenyl-alcohols or allenyl-carboxylic acids. Diastereoselective ring opening of alkynylepoxides has been studied [143,145]. The use of optically active propargyl substrates enables the synthesis of optically active allenes [Eq. (70) 146] [10,140,145-147]. A subtle change of the reaction medium may drastically change the degree of chirality transfer, which has been systematically examined [145]. 

Reaction of ketyls. The carbonyl group reacts with Smlj to generate ketyl species which may be reduced further. Capture of the ketyls with suitable reactants expands the utility of the samarium chemistry. Important reactions include butyrolactone synthesis that is amenable to asymmetric induction when chiral acrylic esters are employed. The reagent system (catalytic in Smij) generated in situ from Smij and Zn-Hg is more economical. The system also contains Lil and MCjSiOTf, and in practice MejSiOTf is added to the mixture of the other components at just the rate to maintain a light blue color (indicating the presence of Smij). When Nilj is added as a catalyst, p-propiolactone instead of acrylic esters can be used. Sometimes steric factors preclude cyclization, and 7-hydroxy esters result. Ketyl addition to acrylamides opens a route to 1,4-amino alcohols. ... 

The synthesis of various phosphonate analogues of aspartic acid, glutamic acid and their homologues and serine phosphate have been reported. The kynurenine phosphinic acid analogue 217 and the corresponding phosphinate 218 have been synthesised from iV-protected 2-amino P-propiolactone (Scheme 27). Kinetic resolution was achieved by esterase-selective hydrolysis of the carboxylate group in the diester. 

This reaction is a consequent continuation of an already described lactone synthesis where (3- or 7-halo-esters were treated with silver isocyanate to form the corresponding P- or 7-lactone (Scheme 75). Via this method TMS P-bromo-propionate 500) affords P-propiolactone 464 ... 

Various substituted lactones were used for enzymatic polyester synthesis via ROP ( )-a-methyl- 3-propiolactone [101], P-methyl-P-propiolactone [78], a-decenyl-P-propiolactone [27], a-dodecenyl-P-propiolactone [46],benzyl-P-D,L-malonolactonate [104], a-methyl-e-caprolactone [96], oc-methyl-8-valerolactone [96], l,4-dioxane-2-one [91], and others (see also Table 4.2). 

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