Lactone Ester Research Articles

Determination of the identity of by‐products in the industrial production of saturated fatty acids

AbstractA technical product of saturated fatty acids has been analyzed to determine the structure of by‐products found in the C20–22 fatty acids manufactured from fish oil. Short‐path distillation of the weakly colored product provided a residue, which was extracted either by supercritical carbon dioxide or by acetone. Extracts and residues were analyzed by size‐exclusion chromatography, supercritical fluid chromatography, and by gas chromatography, the latter combined with mass spectrometry and Fourier‐transform infrared spectroscopy, and by nuclear magnetic resonance spectrometry. A series of homologs of fatty acid dimers was identified as lactone esters. Each homolog also contained several isomers with a varying number of carbon atoms in the two hydrocarbon chains of the dimers. Trimers, containing yellow components, were also present in small amounts, but the structure of the trimers has not been determined yet.

A Novel Polymer for a 193-nm Resist.

A novel methacrylate polymer for a 193-nm resist has been developed. The goal was to enhance the adhesion to Si substrates while ensuring compatibility with a TMAH developer for our methacrylate-based resist. We used two acid-cleavable compounds for the carboxylic acid protective groups: mevalonic lactone and 2-methyl-2-adamantanol. The strong hydrophilicity of mevalonic lactone ester affords good adhesion of the formulated resist patterns to Si substrates. Alicyclic 2-methyl-2-adamantanol provides dry-etch resistance. The acid-catalyzed deprotection of both protective groups generate a large polarity change in the exposed region of the resist films. This allows for high-contrast patterning with high sensitivity using a 2.38% TMAH developer. Using an ArF excimer laser exposure system, 0.17-μm L/S patterns have been resolved.

Synthesis and structural analysis of stereospecific 3,4,5‐trisubstituted γ‐butyrolactone phospholipids

AbstractThe first synthesis of stereospecific 3,4,5‐trisubstituted γ‐butyrolactone phospholipids has been achieved by a ten‐step sequence starting fromN,N‐dimethylacetamide (9). Alkylation of 9 with 1‐bromohexane gaveN,N‐dimethyloctanamide (11), which was subjected to aldol condensation with acrolein and afforded theerythro‐N,N‐dimethyl‐3‐hydroxy‐2‐hexyl‐4‐pentenamide (6) and itsthreo isomer 7, both of which were subsequently converted to the corresponding 3‐oxy(hexanoyl) esters 15 and 16. Stereospecific cyclization of diastereomeric allylic amides (6,7,15 and 16)via iodolactonization gave 3,4,5‐trisubstituted γ‐butyrolactones (19–25) in satisfactory yields (68–89%) and with high stereoselectivity (at least 6∶1), except for thethreo amide 16 (2∶1). Conversion of the 6‐iodo‐group of the major iodolactones 23 and 24 to the corresponding 6‐hydroxy lactones 31 and 32 through a wet Prévost reaction also resulted in 4‐hydroxy lactones 30 and 33, and a mechanism for this reaction is proposed. Further phosphorylation of 4‐ or 6‐hydroxy lactones 30, 31 and 32 with diphenyl chlorophosphate gave the corresponding diphenyl phosphoric acid lactone esters 34, 35 and 36, whereas 33 underwent an elimination reaction under formation of a C(3)−C(4) double bond. Hydrogenolysis of the diphenyl groups of esters 34, 35 and 36 over Adams' catalyst [platinum(IV) oxide] yielded the corresponding phosphoric acid lactone esters 38, 39 and 40, which were finally treated with choline tetraphenylborate to afford the desired lactone phospholipids 41, 42 and 43 in overall yields of 9, 30 and 18%, respectively. The structures of all new compounds were unambiguously assigned by analysis of their1H and13C one‐dimensional and two‐dimensional nuclear magnetic resonance (NMR) spectra obtained on a 300 MHz NMR spectrometer, and the structures were confirmed by low or high resolution mass spectrometry as well as elemental analysis. The stereoisomeric purity of the final products (98.2, 99.0 and 98.5% for 41, 42 and 43, respectively) was determined by high‐performance liquid chromatography.

Structure of a cyclopropapentalene photolysis product of a dibenzobarrelene ester lactone

Photolysis of the dibenzobarrelene ester lactone, C 21 H 16 O 4 (1), can produce several products, the structure of one of which, 8b-methyl 4b-(1-hydroxyethyl)-4b,8b,8c,8d-tetrahydrodibenzo[a,f]cyclopropa[cd]pentalene-8b,8c-dicarboxylate carbolactone (2), has been determined by X-ray methods. The molecule of (2) contains a three-membered ring and has geometry and dimensions similar to those of related materials

ChemInform Abstract: 3a,8b‐Dihydro‐7‐methoxy‐8b‐(trifluoromethyl)‐2H‐indeno(1,2‐b)furan‐2,4(3H)‐dione

3-(Methoxycarbonyl)-4-(3-methoxyphenyl)-4-(trifluoromethyl)-4-butanolide (4) was synthesised from 3-methoxyphenyl trifluoromethyl ketone (1). Hydrolysis of the lactone ester 4, followed by treatment with polyphosphoric acid, led to an intermediate lactone acid 3, which on heating with PCl5 gave the indeno-[1,2-b]furandione 5.

The lactonization of esters of 2-hydroxy-2-trifluoromethyl-4-pentenoic acids

The lactonization of esters of 2-hydroxy-2-trifluoromethyl-4-pentenoic acids

3a,8b‐Dihydro‐7‐methoxy‐8b‐(trifluoromethyl)‐2H‐indeno[1,2‐b]furan‐2,4(3H)‐dione

Abstract3‐(Methoxycarbonyl)‐4‐(3‐methoxyphenyl)‐4‐(trifluoromethyl)‐4‐butanolide (4) was synthesised from 3‐methoxyphenyl trifluoromethyl ketone (1). Hydrolysis of the lactone ester 4, followed by treatment with polyphosphoric acid, led to an intermediate lactone acid 3, which on heating with PCl5 gave the indeno‐[1,2‐b]furandione 5.

Electrophilic Cyclization of Doubly Activated Imines with Lewis Acids and Trialkylsilyl Triflates Synthesis of Pyrrole and Azepine Derivatives

AbstractThe cyclization of the (pentenylimino)malonate 8a gives either the pyrrolidines 11a and 12a or the hexahydro‐1H‐furo[3,4‐b]‐pyrrole 13a as main products depending on the Lewis acid used. The isopropyl ester 8b cyclizes under all reaction conditions preferentially to give the lactone ester 13b. Cyclization of the heptenylimine 9 yields exclusively the epimeric octahydro‐1H‐furo‐[3,4‐b]azepines 17 and 18. The thermodynamically more stable 17 could be obtained in large excess. Saponification and decarboxylation of 17 gives the cyclic nonproteinogenic α‐amino acid derivative 20. The octenylimine 10 could not be cyclized under several conditions tested.

Applications of the 3-methyl-.gamma.-butyrolactone strategy to the synthesis of polypropionates: the Prelog-Djerassi lactonic ester, ent-invictolide, and the C19-C27 fragment of rifamycin S

Applications of the 3-methyl-.gamma.-butyrolactone strategy to the synthesis of polypropionates: the Prelog-Djerassi lactonic ester, ent-invictolide, and the C19-C27 fragment of rifamycin S

Cytochrome P-450-catalyzed hydroxylation and carboxylic acid ester cleavage of Hantzsch pyridine esters.

Cytochrome P-450 (P-450)-catalyzed oxidation of 2,6-dimethyl-4-phenyl-3,5-pyridinedicarboxylic acid diethyl ester gives rise to 2,6-dimethyl-4-phenyl-3,5-pyridinedicarboxylic acid monoethyl ester and to 2-hydroxymethyl-6-methyl-4-phenyl-3,5-pyridinedicarboxylic acid diethyl ester, identified in this work. A pyridine hydroxymethyl diester of the sort of the latter compound is novel; under acidic or dehydrating conditions the diester is readily converted to a cyclic lactone (2-hydroxymethyl-6-methyl-4-phenyl-3,5-pyridinedicarboxylic acid 5-ethyl ester lactone). 2,6-Dimethyl-4-phenyl-3,5-pyridinedicarboxylic acid monoethyl ester was not hydroxylated to form this hydroxymethyl compound or lactone, but 1,4-dihydro-2-hydroxymethyl-4-phenyl-6-methyl-3,5-pyridinedicarboxyli c acid diethyl ester was enzymatically oxidized to give both products. The rates of oxidative carboxylic ester cleavage and methyl hydroxylation varied among individual forms of P-450 tested. Experiments with 2H and 3H labels were used to estimate an intrinsic kinetic deuterium isotope effect of 15 for ethyl ester cleavage by rat liver P-450PB-B in a reconstituted system. Rat liver microsomal systems showed kinetic deuterium and tritium isotope effects of 8 and 11, respectively, and this deuterium isotope effect was not attenuated in either intra- or intermolecular competitive experiments. When deuterium was present in the ethyl (ester) groups, increases in the rate of 2-methyl hydroxylation were observed in rat liver microsomes and with purified P-450 beta NF-B (but not with P-450PB-B). Deuteration of the methyl groups gave rise to kinetic isotope effects of 7-11, but no increases were seen in the rates of ester cleavage. These studies and those on rates of substrate disappearance indicate that isotopically sensitive branching (metabolic switching) observed in these systems is not necessarily bidirectional.

Frequencies and integral intenstities of the lactone and ester carbonyls of natural guaianolides

The frequencies and integral intensities of the IR bands of the stretching vibrations of lactone and acyclic ester carbonyls at C-8 of ten natural guaianolides and their derivatives, and of three model compounds have been studied. The most probable interpretation of the change in the value of AνC=O and νC=O of the lactone carbonyl have been suggested. In elegin and some of its derivatives, acroptilin, chlorohyssopifolin B, and eleganin, a lowering of the values of AνC=0 and νC=0 in comparison with dihydroelegin, hexahydroelegin, and the hydroxylactone of cynaropicrin is caused by nonvalent interactions of the lactone carbonyl with the α-exocyclic double bond. The increase in AνC=O and νC=O in dihydroelegin, hexahydroelegen, and the hydroxylactone of cynaropicrin is due to the angular strain of the γ-lactone ring. It has been shown that in an acyclic side chain at C-8 an increase in the integral intensity and in the frequency of the α,β-unsaturated ester carbonyl relative to guaianolides in which the terminal vinyl group at C-17 is absent is due to a conjugation effect.

ChemInform Abstract: Stereoselective Alkylation of Ester Lactone. Synthesis of d,l‐Geijerone (I) and Formal Synthesis of d,l‐γ‐Elemene (II).

ChemInform Abstract: Stereoselective Alkylation of Ester Lactone. Synthesis of d,l‐Geijerone (I) and Formal Synthesis of d,l‐γ‐Elemene (II).

Anti-inflammatory agents; IV. Structure activity relationships of sesquiterpene lactone esters derived from helenalin.

Anti-inflammatory agents; IV. Structure activity relationships of sesquiterpene lactone esters derived from helenalin.

Induction of cytogenetic damage by modified steroidal derivatives of p-bis(2-chloroethyl)aminophenylacetic acid in human lymphocytes

The effect of modified steroids, containing alkylating agents, on SCE rates and on cell kinetics in cultured human lymphocytes was studied. The homo-aza-steroidal ester of p-bis(2-chloroethyl)aminophenylacetic acid (ASE) was found to be the most effective in causing markedly increased SCE rates and cell division delays. The androsterone ester of p-bis(2-chloroethyl)aminophenylacetic acid (AE-CAPA) was found to be next in order of effectiveness with the lactone ester (LE-CAPA), chlorambucil ester 3β-hydroxy-13a-amino-13, 17-seco-5a-androstan-17-oic-13,17-lactam (CBC-HAAL) and chlorambucil (CBC) following. p-bis(2-chloroethyl)aminophenylacetic acid (CAPA) had only a small effect and 3β-hydroxy-13a-amino-13,17-seco-5a-androstan-17-oic-13,17-lactam (HAAL) had no effect at all. A correlation between potency for SCE induction, effectiveness in cell division delay and previously established antitumor activity of these drugs was observed.

Stereoselective Alkylation of Ester Lactone. Synthesis of dl-Geijerone and Formal Synthesis of dl-g-Elemene

Synthese a partir du monoester de methyle de l'acide cyclohexene-4 dicarboxylique-1,2 via l'iodo-4 oxo-7 oxa-6 bicyclo [3.2.1] octanecarboxylate-2 de methyle

Total Synthesis of Neomethynolide

Abstract Neomethynolide (1), the aglycone of a twelve-membered ring macrolide, neomethymycin, was totally synthesized in its optically active form via 8,9-didehydro-1. The construction of the skeleton was carried out by condensing a stereoselectively synthesized fragment, 4-t-butyldimethylsiloxy-5-(2-methoxyethoxymethoxy)3-methyl-1-hexyne, with Prelog-Djerassi lactonic ester, and mixed anhydride method was used for the lactonization of an intermediary hydroxy acid. The full stereochemistry of 1 was established by this synthesis.

Heat stability of aromatic polyesters

Abstract A study was made of the behaviour of polyarylates of different chemical structure under conditions of high-temperature breakdown in inert atmosphere and in steam. The difference in the heat stability of cardic polyesters, due to the mutual effect of the lactone ring and ester group in the polymer chain, was shown.

ChemInform Abstract: A REACTIVE LACTONIC DIENOPHILE ‐ 3‐CARBETHOXY‐5,5‐DIMETHYL‐2(5H)‐FURANONE. APPLICATION TO THE SYNTHESIS OF A MONOTERPENOID LACTONE

Abstract3‐Curbethoxy‐5.5‐dimethyl‐2(5H)‐furanone.

A reactive lactonic dienophile – 3-carbethoxy-5,5-dimethyl-2(5H)-furanone. Application to the synthesis of a monoterpenoid lactone

In contrast to the low dienophilicity generally observed for α,β-unsaturated lactones, the title compound 2 is shown to be a reactive dienophile. Under stannic chloride catalysis, it undergoes Diels–Alder reaction region- and stereoselectively with a variety of dienes at room temperature. The synthesis of (±)-o-mentha-1,3-dien-1→8-olide (20) has been achieved by a two-step sequence using lactone ester 2. Addition of 2 to 1-acetoxy-1,3-butadiene afforded epimeric acetoxy lactones 12 and 13 which were converted to the monoterpenoid lactone 20 by treatment with lithium iodide dihydrate in collidine.

γ‐Lactones from malonic acid derivatives

AbstractThe acid catalyzed cyclization of isopropylidene malonate derivatives of ketones to form α‐earboxy‐γ‐lactones has been shown to occur with boron trifluoride etherate or p‐toluenesulfonic acid, as well as with concentrated sulfuric or polyphosphoric acids. A similar cyclization of a diethyl ylidenemalonate to a lactone ester, in relatively poor yield, has also been accomplished. Acid catalyzed cyclization of the ylidenemalononitrile derived from pinacolone to form an α‐carbamoyl‐γ‐lactone has been shown to occur with rearrangement. However, that derived from 2,2‐dimethyleyclohexanone cyclized to the secondary carbon of the ring without rearrangement. The isopropylidene malonate derivatives of several ring‐substituted and bridged ketones have been converted to α‐earboxy‐γ‐laetones without rearrangement.