- Preparation of mono-substituted malonic acid half oxyesters (SMAHOs)
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The use of mono-substituted malonic acid half oxyesters (SMAHOs) has been hampered by the sporadic references describing their preparation. An evaluation of different approaches has been achieved, allowing to define the best strategies to introduce diversity on both the malonic position and the ester function. A classical alkylation step of a malonate by an alkyl halide followed by a monosaponification gave access to reagents bearing different substituents at the malonic position, including functionalized derivatives. On the other hand, the development of a monoesterification step of a substituted malonic acid derivative proved to be the best entry for diversity at the ester function, rather than the use of an intermediate Meldrum acid. Both these transformations are characterized by their simplicity and efficiency, allowing a straightforward access to SMAHOs from cheap starting materials.
- Condon, Sylvie,Le Gall, Erwan,Pichon, Christophe,Presset, Marc,Xavier, Tania
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p. 2085 - 2094
(2021/09/02)
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- COMPOSITIONS AND METHODS FOR MAKING HYBRID POLYPEPTIDES
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Compositions and methods of making hybrid polypeptides and other polymers are disclosed. For example, functionalized tRNA having a functional molecule including a benzoic acid or benzoic acid derivative acylated to the 3' nucleotide of a tRNA are provided
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Page/Page column 112
(2020/12/29)
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- Synthesis of Monothiomalonates – Versatile Thioester Enolate Equivalents for C–C Bond Formations
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Monothiomalonates (MTMs) are surrogates of thioester enolates that allow for stereoselective C–C bond formations under mild conditions and thereby afford access to synthetically versatile thioester derivatives. Here we present a straightforward synthetic route to MTMs that proceeds through nucleophilic ring-opening of Meldrum's acid derivatives followed by O-alkylation of the resulting malonic acid half thioesters with alkyl triflates or acetimidates as electrophiles. The method affords MTMs in overall yields of 34?–?92% and allows for variations of the oxo- and thioester moieties as well as the substituent at the C(α) position.
- Engl, Oliver D.,Saadi, Jakub,Cosimi, Elena,Wennemers, Helma
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- Di- and triarylmethylium ions as probes for the ambident reactivities of carbanions derived from 5-benzylated Meldrum's acid
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The kinetics of the reactions of carbocations with carbanions 1 derived from 5-benzyl-substituted Meldrum's acids 1-H (Meldrum's acid=2,2-dimethyl-1,3- dioxane-4,6-dione) were investigated by UV/Vis spectroscopic methods. Benzhydryl cations Ar2CH+ added exclusively to C-5 of the Meldrum's acid moiety. As the second-order rate constants (kC) of these reactions in DMSO followed the linear free-energy relationship lg k=s N(N+E), the nucleophile-specific reactivity parameters N and s N for the carbanions 1 could be determined. In contrast, trityl cations Ar3C+ reacted differently. While tritylium ions of low electrophilicity (E-2) reacted with 1 through rate-determining β-hydride abstraction, more Lewis acidic tritylium ions initially reacted at the carbonyl oxygen of 1 to form trityl enolates, which subsequently reionized and eventually yielded triarylmethanes and 5-benzylidene Meldrum's acids by hydride transfer.
- Chen, Xi,Tan, Yue,Berionni, Guillaume,Ofial, Armin R.,Mayr, Herbert
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p. 11069 - 11077
(2014/10/15)
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- Mechanistic investigation of the selective reduction of Meldrum's acids to β-hydroxy acids using SmI2 and H2O
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The mechanism of a recently reported first mono-reduction of cyclic 1,3-diesters (Meldrum's acids) to β-hydroxy acids with SmI 2-H2O has been studied using a combination of reactivity, deuteration, kinetic isotope and radical clock e
- Szostak, Michal,Lyons, Sarah E.,Spain, Malcolm,Procter, David J.
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supporting information
p. 8391 - 8394
(2014/07/22)
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- A facile route to ketene-functionalized polymers for general materials applications
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Function matters in materials science, and methodologies that provide paths to multiple functionality in a single step are to be prized. Therefore, we introduce a robust and efficient strategy for exploiting the versatile reactivity of ketenes in polymer
- Leibfarth, Frank A.,Kang, Minhyuk,Ham, Myungsoo,Kim, Joohee,Campos, Luis M.,Gupta, Nalini,Moon, Bongjin,Hawker, Craig J.
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scheme or table
p. 207 - 212
(2010/10/20)
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- One Pot Synthesis of Monoalkylated and Mixed, Dialkylated Meldrum's Acid Derivatives
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A simple one pot method, involving sequential Knoevenagel condensation of Meldrum's acid with aromatic aldehydes, conjugate reduction of ylidene Meldrum's acid using sodium borohydride followed by alkylation, to prepare mixed dialkylated derivatives of Meldrum's acid is described.
- Desai, Uday V.,Pore,Mane,Solabannavar,Wadgaonkar
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- ALKYLATION STUDIES WITH ISOPROPYLIDENE MALONATE UNDER PTC AND DIBENZO-(18)-CROWN-6
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Isopropylidene malonate (2,2-dimethyl-4,6-dioxo-1,3-dioxane, Meldrum's acid) has a high acidity (pK1=4.97), a rigid cyclic structure and can undergo easy hydrolysis.It has become an attractive reagent in organic synthesis.For example, it can readily undergo Knoevenagel condensation, Michael addition, and acylation reactions.However, few reports on its alkylation are reported.On alkylation of isopropylidene malonate under (20 percent aqueous sodium hydroxide (TEBA) the ring underwent cleavage and the main product was α,α-dimethylmalonic acid methyl ester.This problem was solved by the use of solid potassium carbonate in place of 20 percent aqueous sodium hydroxide to avoid hydrolysis and let the reaction undergo under solid-liquid phase-transfer conditions.However, these require reflux conditions and prolonged reaction times (4 to 8 h).Our results on the use of combination of a phase-transfer catalyst and crown ether promoted us to investigate the bis alkylation studies with isopropylidene malonate.
- Kore, A. R.,Mane, R. B.,Salunkhe, M. M.
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p. 643 - 646
(2007/10/02)
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- HIV PROTEASE INHIBITORS
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Peptide mimics, having a constrained peptide backbone conformation, are HIV protease inhibitors. A compound of this invention is, for example, 3-Benzyl-5(alaninyl-1-aminoethyl)-2,3,6,7-tetrahydro-N-azepinyl-2-propionyl-valinyl-valinyl methyl ester.
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- Process for the preparation of 1,3-dioxane-4,6-dione derivates
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The invention relates to a process for preparing the compounds of general formula (I), wherein Rmeans hydrogen, C1 4alkyl or (C1 5alkoxy)carbonyl group; R1stands for a C1 6 alkyl, (C1 5alkyl)carbonyl, (C1 5alkoxy)carbonyl or (C1 5alkoxy)carbonyl-(C1 4alkyl) group; or a cyclohexyl group; or a cyclopentyl group; or a phenyl, furyl or thienyl group, optionally substituted, or a b-CH=CH group, wherein b is a phenyl group; or R and R1together form a C4 5alkylene group; R2represents a C1 5alkyl or phenyl group; R3means hydrogen or a C1 4alkyl group; or R2 and R3together form a pentylene group. By reacting a compound of general formula (II) with a compound of general formula (III) and/or reducing a compound of the general formula (IV),
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- Reduction of substituted isopropylidene methylenemalonates using borohydride exchange resin
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Substituted isopropylidene methylenemalonates (Knovenagel type products) (1-7) derived from Meldrum's acid (2,2-dimethyl-1,3-dioxan-4,6-dione) are readily reduced by borohydride exchange resin under mild reaction conditions to give 8-14 in high yields and
- Kanade, A. S.,Sagar, A. D.,Salunkhe, M. M.
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p. 896 - 897
(2007/10/02)
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- Monoalkylation studies with Meldrum's acid
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A general procedure for the monoalkylation of Meldrum's acid (1) is described.Meldrum's acid anion in DMF is slowly added to alkyl halides in DMF to give monoalkylated products.Lower primary as well as highly reactive halides give a mixture of mono- and b
- Kumbhar, Pramod P,Salunkhe, Manikarao, M,Mane, Ramchandra B
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- ONE POT SYNTHESIS OF MONOSUBSTITUTED ISOPROPYLIDENE MALONATES
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Monosubstituted isopropylidene malonates have been synthesized from Meldrum's acid and carbonyl compounds in the presence of sodium hydrogentelluride as a one pot reaction.
- Huang, Xian,Xie, Linghong
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p. 1701 - 1708
(2007/10/02)
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- Synthesis of partially modified retro-inverso substance P analogues and their biological activity
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Partial retro-inverso modification of a single peptide bond was applied to pGlu-Phe-Phe-Gly-Leu-Met-NH2 (I), a C-terminal hexapeptide analogue of the neuropeptide substance P. Two analogues with reversed peptide bonds, between the pGlu-Phe and
- Chorev,Rubini,Gilon,Wormser,Selinger
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p. 129 - 135
(2007/10/02)
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- Borohydride reduction of substituted isopropylidene methylenemalonates
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Knoevenagel-type products derived from Meldrum's Acid are readily reduced by sodium borohydride to give monosubstituted isopropylidene malonates in high yield.
- Wright, Allen D.,Haslego, Mark L.,Smith, Francis X.
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p. 2325 - 2326
(2007/10/09)
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