The formylacetate synthon. Studies related to the synthesis of the penam and oxapenam ring systems

1987 ◽  
Vol 65 (1) ◽  
pp. 26-30 ◽  
Author(s):  
Saul Wolfe ◽  
Roman Z. Sterzycki
Keyword(s):  
Acetic Acid ◽  
Acid Ester ◽  
Ring Closure ◽  
Protecting Group ◽  
Ring Systems

Methyl penicillanate has been synthesized by condensation of D-penicillamine with three different variations of the synthon RO2CCH2CHO, followed by esterification of the resulting 4-carboxythiazolidine-2-acetic acid ester, removal of R, and Mukaiyama ring closure. The conditions for the synthesis of an analogous 4-carboxyoxazolidine-2-acetic acid ester, containing an N-benzoyl protecting group, have been worked out. The condensation of threonine with diethinylketone does not lead directly to a vinylogous oxapenam.

Ring Closure of (2-Acylaryl)acetic Acid Derivatives

2003 ◽  
pp. 1
Author(s):  
M. Nógrádi
Keyword(s):  
Acetic Acid ◽  
Ring Closure

AN INDOLE-3-ACETIC ACID ESTER OF A CELLULOSIC GLUCAN

1973 ◽  
pp. 297-314 ◽  
Author(s):  
Robert S. Bandurski ◽  
Z. Piskornik
Keyword(s):  
Acetic Acid ◽  
Acid Ester ◽  
Indole 3 Acetic Acid

The 2,2,2-Trichloroethyl Group for Carboxyl Protection During Peptide Synthesis

1973 ◽  
Vol 51 (2) ◽  
pp. 208-214 ◽  
Author(s):  
Bernard Marinier ◽  
Yoon C. Kim ◽  
Jean-Marie Navarre
Keyword(s):  
Amino Acids ◽  
Acetic Acid ◽  
Peptide Synthesis ◽  
Optical Activity ◽  
Selective Removal ◽  
Acid Chlorides ◽  
Protecting Group

The 2,2,2-trichloroethyl esters of several N-carbobenzoxy-amino acids were prepared by reacting the corresponding acid chlorides with trichloroethanol and the carbobenzoxy groups were selectively removed by HBr–AcOH. The resulting esters were then coupled with various N-carbobenzoxy-amino acids or peptides using dicyclohexylcarbodiimide in acetonitrile to give N-carbobenzoxy-peptide trichloroethyl esters. The selective removal of the trichloroethyl protecting group was effected by reduction using zinc in acetic acid. The optical activity of the N-carbobenzoxy-peptides so obtained agreed well with the values reported in the literature. The overall results suggest that the 2,2,2-trichloroethyl group could be useful for carboxyl protection during peptide synthesis.

scholarly journals Photochemical and thermal intramolecular 1,3-dipolar cycloaddition reactions of new o-stilbene-methylene-3-sydnones and their synthesis

2011 ◽  
Vol 7 ◽  
pp. 1663-1670 ◽  
Author(s):  
Kristina Butković ◽  
Željko Marinić ◽  
Krešimir Molčanov ◽  
Biserka Kojić-Prodić ◽  
Marija Šindler-Kulyk
Keyword(s):  
Acetic Acid ◽  
Photochemical Reactions ◽  
Acid Anhydride ◽  
Ring Closure ◽  
Dipolar Cycloaddition ◽  
Cycloaddition Reactions ◽  
Thermal Reactions

New trans- and cis-o-stilbene-methylene-sydnones 3a,b were synthesized by transforming the trans- and cis-o-aminomethylstilbene derivative, obtained by reduction of corresponding o-cyano derivatives, into glycine ester derivatives (43 and 31% yield) followed by hydrolysis (90 and 96% yield), nitrosation and ring closure with acetic acid anhydride (30 and 40% yield). The products were submitted to photochemical and thermal intramolecular [3 + 2] cycloadditions to afford diverse heteropolycyclic compounds. Photochemical reactions afforded cis-3-(4-methylphenyl)-3a,8-dihydro-3H-pyrazolo[5,1-a]isoindole (11, 12.5% yield) and trans-3-(4-methylphenyl)-3a,8-dihydro-3H-pyrazolo[5,1-a]isoindole (12, 5% yield). Thermal reactions afforded 3-(4-methylphenyl)-3,3a,8,8a-tetrahydroindeno[2,1-c]pyrazole (14, 50% yield) and 11-(4-methylphenyl)-9,10-diazatricyclo[7.2.1.02,7]dodeca-2,4,6,10-tetraene (15, 22% yield).

Synthesis of l,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acids and homologous pyridine and azepine analogues thereof

1982 ◽  
Vol 60 (18) ◽  
pp. 2295-2312 ◽  
Author(s):  
Humberto Carpio ◽  
Edvige Galeazzi ◽  
Robert Greenhouse ◽  
Angel Guzmán ◽  
Esperanza Velarde ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Carboxylic Acid ◽  
Acid Derivative ◽  
Sodium Borohydride ◽  
Acid Ester ◽  
Keto Acid ◽  
Acid Salt ◽  
Keto Ester ◽  
Acetic Acid Esters ◽  
Acid Esters

Several syntheses of the previously unknown 1,2-dihydro-3H-pyrrolo[1,2-a]pyrrole-1-carboxylic acid and various 5- and 6-substituted derivatives thereof have been devised. Some of these processes have been extended to the heretofore unreported 5,6,7,8-tetrahydropyrrolo[1,2-a]pyridine-8-carboxylic acid and 5,6,7,8-tetrahydro-9H-pyrrolo[1,2-a]azepine-9-carboxylic acid derivatives.Two new processes were developed for the conversion of pyrroles into the corresponding pyrrol-2-acetic acid esters. Both processes were based on the use of the readily available ethoxalylpyrrole derivatives as the starting material. One sequence involved saponification of the α-keto ester, followed by Wolff–Kishner reduction of the crude α-keto acid salt and subsequent esterification of the acetic acid derivative thus produced. The second synthesis commenced with reduction of the 2-ethoxalpyrrole with sodium borohydride to the α-hydroxy ester, which was further reduced to the acetic acid ester with an equimolar mixture of triphenylphosphine and triphenylphosphine diiodide.

scholarly journals Evaluation of an acetic acid ester of monoglyceride as a suppository base with unique properties

2001 ◽  
Vol 2 (3) ◽  
pp. 32-38 ◽  
Author(s):  
Alekha K. Dash ◽  
Greggrey C. Cudworth
Keyword(s):  
Acetic Acid ◽  
Acid Ester ◽  
Suppository Base

Benzoxathiete and related structures: experimental and quantum chemical studies

1990 ◽  
Vol 68 (11) ◽  
pp. 1950-1960 ◽  
Author(s):  
Ali Naghipur ◽  
Krzysztof Reszka ◽  
J. William Lown ◽  
Anne-Marie Sapse
Keyword(s):  
Hydrogen Peroxide ◽  
Acetic Acid ◽  
Quantum Chemical ◽  
Spin Trapping ◽  
Ring Closure ◽  
Paramagnetic Resonance ◽  
Valence Tautomerism ◽  
Carbon Centered Radical ◽  
Chemical Studies ◽  
Abinitio Calculations

The products, plausible intermediates, and their mechanisms of formation in the aprotic diazotization of 2-[(2-acetoxyethyl)-sulfinyl (and sulfonyl)]anilines with isoamyl nitrate have been investigated by experimental and quantum chemical methods. Oxidation of 1,2,3-benzthiadiazole with hydrogen peroxide in acetic acid affords 1,2,3-benzthiadiazole-1-oxide, 13. The thermal stability of 13 up to 135 °C, together with EPR evidence which disfavors an aryldiazenyl radical precursor, discount 13 as an intermediate in the formation of benzoxathiete 14 or its valence tautomer 17 during aprotic diazotization of the sulfinylanilines. Electron paramagnetic resonance evidence in conjunction with spin trapping indicates an intermediate arylaminyl radical. This evidence, taken together with abinitio calculations of optimized geometries energies and energy differences for biradical intermediate 15, favors a mechanism of formation of benzoxathiete 14 via aryldiazoate anhydride 5 thence to rapid ring closure of carbon-centered radical 8. Further oxidation of 1,2,3-benzthiadiazole-1-oxide, 13, with hydrogen peroxide in methanol – acetic acid affords biphenylene and dibenzo-1,4-oxathiane-S-oxide, 38. Rose bengal sensitized photooxidation of 1,2,3-benzthiadiazole affords 13, biphenylene, and 38. Formation of the latter, in which one of the original S—O bonds has been broken, requires the formation of benzoxathiete-S-oxide, 34, and its rapid valence tautomerism to ketosulfine 36 and (2 + 4) cycloaddition of 36 to the simultaneously generated dehydrobenzene to give 38. Both ring closure of singlet biradical 35 to 34 and valence tautomerism of the latter to 36 are predicted by abinitio calculations to be facile and exothermic. In contrast to the aprotic diazotization of 2-[(2-acetoxyethyl)sulfinyl]anilines, the reaction of isoamyl nitrite with the corresponding sulfonyl anilines may plausibly follow a mechanism via 1,2,3-benzthiadiazole-1,1-dioxide 33 owing to the thermal instability of the latter and supported by abinitio treatments of the energetics of the processes involved. In addition EPR evidence, in conjunction with spin trapping of carbon centered radicals, support the viability of the pathway via 23, 25, 28, and 16 to biphenylene 20. The abinitio calculations of the energy differences between the reaction intermediates and estimates of the activation energies elucidated several aspects of these novel reactions. Keywords: benzoxathiete, abinitio calculations, valence tautomerism.

Neighbouring group participation by the carboxy group in the solvolysis of the dipeptides in acetic acid

1977 ◽  
Vol 30 (5) ◽  
pp. 1025 ◽  
Author(s):  
RJL Martin ◽  
DS Schneider ◽  
CH Skovron ◽  
DLH Yiu
Keyword(s):  
Acetic Acid ◽  
Acid Solution ◽  
Normal Mode ◽  
Carboxy Group ◽  
Acetic Acid Solution ◽  
Ring Closure ◽  
Medium Effect ◽  
Infrared Analysis ◽  
Complete Disappearance ◽  
Absorption Frequencies

The acid-catalysed solvolysis of the dipeptides in acetic acid solution occurs readily both in the presence and absence of water. The rates increase with increasing methylation, which is consistent with a mechanism involving a ring-closure pathway by the terminal carboxy group. The experimentally determined rate law is: f × rate × [H2O]/[dipeptidium(1+) ClO4-][ΣH+] = k1 + k2[H2O]2 where f is the salt effect factor and ΣH+ is the acetic acidium perchlorate concentration after correcting for the presence of oxonium perchlorate. The k1 values increase with increasing methylation, as required for a ring-closure mechanism, and the inverse water term in this component of the rate is ascribed to a medium effect. The ratecontrolling step is defined as being the acid-catalysed ring fission of a rapidly formed intermediate, oxazalone acetic acid solvate. The k2 component of the rate is first order with respect to water and would appear to refer to the normal mode of solvolysis. But the much higher values of k2 for the heavily methylated compounds as compared with Gly-Gly are incompatible with the much lower activities shown by these compounds when reacting by the normal mode of solvolysis. Since k2 passes through a minimum with increasing methylation, it is suggested that it is a composite of the normal and ring-closure modes of solvolysis. The rate-controlling step for this latter reaction is the acid-catalysed reaction of water with the oxazolone acetic acid solvate. The increasing rates arising from increasing methylation are due to increasing stabilities of the oxazolone solvate ring systems resulting in a kinetically favourable displacement of this equilibrium towards the ring system. Infrared analysis shows that the oxazolone of Aibu-Aibu readily undergoes a fast reaction with acidified acetic acid to form a stable acetic acid solvate with the complete disappearance of all oxazolone absorption frequencies. Aibu-Aibu on heating in acidified acetic acid solution rapidly forms the same oxazolone acetic acid solvate with no evidence of any oxazolone absorption frequencies. The solvolysis of optically active Gly-Val demonstrates that the oxazolone is not formed as an intermediate because the Val produced retains its optical activity with no evidence of any racemization.

scholarly journals Effect of Acetic Acid Ester and KUMGANG Medicine Stone in Silkworm Rearing with Artificial Diet and Mulberry

2021 ◽  
pp. 01-11
Author(s):  
Kim Myong Guk ◽  
Cha JinMyong ◽  
Kim JongGill ◽  
Son YuHyok ◽  
Kim Chan Ryong ◽  
...  
Keyword(s):  
Body Weight ◽  
Acetic Acid ◽  
Acid Ester ◽  
Growth And Development ◽  
Artificial Diet ◽  
Feeding Habit ◽  
The Body ◽  
Inorganic Salts ◽  
Mineral Salts ◽  
Disease Occurrence

Raising silkworms by using artificial feed is not affected by the seasons and can realize the industrialization of silkworm breeding. The study has been conducted the research for using acetic acid as the material of organic acid in fresh mulberry and KUMGANG medicine stone in which various mineral salts are many contained as the material of inorganic salts in artificial feed. When acetic acid esterfied is added to artificial diet as rate of 3.3%, the setae dispersion within 48h was above 98% and the incentive was 100%. Antiseptic effect on artificial feed has been maintained for 90h since falling the feed. Acetic acid has raised the feeding habit on the 3rd instar larvae as the rate of 118.5% to128.4% and the body weight as the rate of 104.5%. KUMGANG medicine stone of the rate of 1% on artificial feed has promoted the growth and development of young silkworm. In the autumn with bad condition on rearing, KUMGANG medicine stone has been decreased the disease occurrence in larvae and raised the quality and yield of cocoon.

Sign in / Sign up

Export Citation Format

Share Document