Allylstannation: VII. Preparation of carboxylic acid 1-alkene-4-yl and 1-alkyne-4-yl esters by transalkoxylation of 4-n-dibutylchlorostannoxy-1-alkenes and 4-n-dibutylchlorostannoxy-1-alkynes with acyl chlorides

Carboxylic acid 1-alkene-4-yl and 1-alkyne-4-yl, esters (RCH(CH₂CHCH₂)OCOR′ ad RCH(CH₂CCH)OCOR′, R = R′ or R ≠ R′ = alkyl or alkenyl group) can be readily prepared in high yields by transalkoxylation reactions between 4-n-dibutylchlorostannoxy-1-alkenes or 4-n-dibutylchlorostannoxy-1-alkynes with acyl chlorides. This represents a general route for preparation of esters containing allyl or propargyl groups.     

An Efficient Synthesis of the Indole Acetic Acid Metabolite of MK-0462

A palladium-catalyzed coupling of iodoaniline 2 with bis-TES propargyl alcohol 3 gives indole-3-methanol 4b in 72% yield. Displacement of the hydroxy group of 4b by sodium cyanide followed by hydrolysis of the cyano group and desilylation provides the indole acetic acid metabolite, L-749,335 (1), of the 5-HT_1D receptor agonist MK-0462.     

Synthesis of N-[5-alkoxy-2(5H)-furanonyl] amino acid propargyl esters

Using K₂CO₃ as a base and CH₃CN as solvent, different kinds of N-[5-alkoxy-2(5H)-furanonyl] amino acids were reacted with propargyl bromide via substitution reaction at 40?°C to give 16 N-[5-alkoxy-2(5H)-furanonyl] amino acid propargyl esters with the yields of 44?C85% (mostly over 74%). The structures of all newly synthesized compounds were elucidated and confirmed by FTIR, UV, ¹H NMR, ¹³C NMR, MS, and elemental analysis. The rapid, efficient, and brief synthesis of the series propargyl esters with multiple bioactive units, will afford not only a basis for the activity test of potential drug molecules, but also an important synthetic strategy for 2(5H)-furanone derivatives with polyfunctional groups.     

α-(Benzotriazol-1-YL)Propargyl Ethyl Ethers: Novel Precursors to Enediynes,Enynes and Dienynes

Deprotonated 1-(benzotriazol-1-yl)propargyl ethyl ethers react with propargyl, allyl and alkyl bromides to give the expected substituted derivatives 2, 4 and 9, respectively. Subsequent eliminations of the benzotriazolyl group upon treatment with NaH or ZnBr₂, and elaboration of the acetylene group, generate ethoxy substituted enediynes 3, 6, 8, dienynes 7 and enynes 12. Grignard reagents or LiAlH₄ convert 9 into α-ethoxy substituted alkynes 10 and 11.     

Silicon-containing esters of α-cyanoacrylic acid: synthesis and properties

A number of cyanoacetates have been synthesized: cyanoacetoxymethyitrimethylsilane (1), cyanoacetoxymethylpentamethyldisiloxane (2), cyanoacetoxyetoxymethylpentamethyldisiloxane (3). They were converted by the Knoevenagel reaction to novel esters of a-cyanoacrylic acid (4–13) containing silicon atoms in the ester groups and having the general formula RCH=C(CN)COOCH₂X (where R=H, 4-MeOC₆H₄, MeCH=CH, 2-furyl; X=SiMe₃, SiMe₂OSiMe₃, CH₂OCH₂SiMe₂OSiMe₃). These compounds are capable of copolymerization with esters of cyanoacrylic acid which are the precursors to adhesives for cold curing.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 949–952, May, 1993.     

Synthesis of Uridine Derivatives Containing Amino Acid Residues

Abstract

Convenient synthesis of uridine derivatives containing amino acid residues were carried out successfully by reacting triazolated uridine with the hydrochloride salts of some amino acid esters, which provides a general method for the direct introduction of amino acid group onto nucleoside residue.     

Reactions of a Ruthenium Complex with Substituted N‐Propargyl Pyrroles

In an investigation into the chemical reactions of N‐propargyl pyrroles 1 a – c , containing aldehyde, keto, and ester groups on the pyrrole ring, with [Ru]?Cl ([Ru]=Cp(PPh₃)₂Ru; Cp=C₅H₅), an aldehyde group in the pyrrole ring is found to play a crucial role in stimulating the cyclization reaction. The reaction of 1 a , containing an aldehyde group, with [Ru]?Cl in the presence of NH₄PF₆ yields the vinylidene complex 2 a , which further reacts with allyl amine to give the carbene complex 6 a with a pyrrolizine group. However, if 1 a is first reacted with allyl amine to yield the iminenyne 8 a , then the reaction of 8 a with [Ru]?Cl in the presence of NH₄PF₆ yields the ruthenium complex 9 a , containing a cationic pyrrolopyrazinium group, which has been fully characterized by XRD analysis. These results can be adequately explained by coordination of the triple bond of the propargyl group to the ruthenium metal center first, followed by two processes, that is, formation of a vinylidene intermediate or direct nucleophilic attack. Additionally, the deprotonation of 2 a by R₄NOH yields the neutral acetylide complex 3 a . In the presence of NH₄PF₆, the attempted alkylation of 3 a resulted in the formation the Fischer‐type amino–carbene complex 5 a as a result of the presence of NH₃, which served as a nucleophile. With KPF₆, the alkylation of 3 a with ethyl and benzyl bromoacetates afforded the disubstituted vinylidene complexes 10 a and 11 a , containing ester groups, which underwent deprotonation reactions to give the furyl complexes 12 a and 13 a , respectively. For 13 a , containing an O‐benzyl group, subsequent 1,3‐migration of the benzyl group was observed to yield product 14 a with a lactone unit. Similar reactivity was not observed for the corresponding N‐propargyl pyrroles 1 b and 1 c , which contained keto and ester groups, respectively, on the pyrrole ring.     

Synthesis and complex-forming properties of crown ethers incorporating glucuronic acid moieties

Crown ethers1 and4 of the 18-crown-6 type containing two glucose units have been oxidised by KMnO₄ into mono- and dicarboxylic acid derivatives (5 and11), and derivatives with different lipophilicities of the above crown ethers, namely the acetyl, benzyl and butyl derivatives (8–10, 13, 14) and methyl esters (6 and12) have been synthesizedThe association constants (K _a) with Li, Na, K and NH₄ cations measured in CHCl₃ indicate that complexing ability increases on introduction of carboxy groups, and selectivity changes in favour of the Na cation. These compounds were able to transport alkyl-ammonium salts through a CHCl₃ liquid membrane, displaying, however, no chiral recognition ability.     

Detailed studies on the reduction of aliphatic 3-, 4-, 6-, and 13-oximino esters: Synthesis of novel isomeric amino esters,oximino alcohols,and amino alcohols

The preparation of novel 3-, 4-, 6-, and 13-amino-tetradecanoic acid methyl esters (2a–d) obtained by the reduction of 3-, 4-, 6-, and 13-oximino-tetradecanoic acid methyl esters (1a–d), was investigated. Oximino esters were reduced to afford the corresponding amino esters using NaBH₄–ZrCl₄ reducing system with good yields (58–82%). However, the reduction of oximino esters with LiAlH₄ and BH₃. Tetrahydrofuran gave the corresponding novel 3-, 4-, 6-, and 13-oximino alcohols (3a–d), and 3-, 4-, 6-, and 13-amino alcohols (4a–d) respectively with good chemical yields.     

Synthesis and biological evaluation of nigranoic acid esters as novel human neutrophil elastase inhibitors

Human neutrophil elastase (HNE) has been implicated as a major contributor in the pathogenesis of diseases, such as lung disorders and other inflammatory diseases. A series of 12 new nigranoic acid esters were regioselectively synthesised in good yields and evaluated for HNE inhibitory activity. Nigranoic acid exhibited significant inhibitory activity against HNE with the IC₅₀ value of 3.77 μM, and six esters displayed considerable inhibitory effects on HNE with IC₅₀ values in the range of 2.61–8.95 μM. The nigranoic acid esters having phenyls substituted with bromine and trimethoxyls (3h and 3b) showed stronger inhibitory activity on HNE than nigranoic acid.     

Deprotection‐free preparation of propargyl ether‐containing phosphinated benzoxazine and the structure–property relationship of the resulting thermosets

Generally, protection and deprotection procedures of amino groups are required in preparing propargyl ether‐containing benzoxazines. In this study, we report a facile, deprotection‐free preparation of a propargyl ether‐containing phosphinated benzoxazine (2) from the nucleophilic substitution of a phenolic OH‐containing phosphinated benzoxazine (1) and propargyl bromide in the catalysis of potassium carbonate. The structure of (2) was characterized and confirmed by a high‐resolution mass spectrum, ¹H, ¹³C, ¹H‐¹H, ¹H‐¹³C nuclear magnetic resonance (NMR) spectra, and X‐ray single crystal diffractogram. infrared (IR) and differential scanning calorimetry were used to monitor the ring‐opening of benzoxazine and crosslinking of propargyl ether. The microstructure and the structure–property relationship of the resulting homopolymers and copolymers are discussed. The T_g of homopolymer of (2) is 208 °C by dynamic mechanical analysis, the coefficient of thermal expansion is 43 ppm/°C, and T_d 5% (N₂) is 393 °C, respectively, which are higher than those of the homopolymer of (1) . Similar trends were observed in the copolymerization system. The results demonstrate the beneficial effect of crosslinking afforded by the propargyl ether group is higher than that by the phenolic OH group. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Synthesis of Novel New 2-(2-(4-((3,4-Dihydro-4-oxo-3-aryl quinazolin-2-yl)methyl)piperazin-1-yl)acetoyloxy)-2-phenyl Acetic Acid Esters

Stereoselective diazotization of (S)-2-amino-2-phenyl acetic acid (L-phenyl glycine) (4) with NaNO₂ in 6% H₂SO₄ in a mixture of acetone and water gave optically pure (S)-2-hydroxy-2-phenyl acetic acid (L-mandelic acid) (5). Esterification, gave (S)-2-hydroxy-2-phenyl acetic acid esters (6). The latter was treated with chloroacetyl chloride in the presence of triethylamine (TEA) in dichloromethane (DCM) to yield (S)-2-chloroacetyloxy phenyl acetic acid ester (2). In another sequence, the reaction of 2-(chloromethyl)-3-arylquinazolin-4(3H)-one (9) treated with N-Boc piperazine, followed by deprotection of the Boc group, to obtain 3-aryl-2-((piperazin-1-yl)methyl) quinazolin-4(3H)-one (3). Reaction of 2 with 3 in the presence of K₂CO₃ and KI gave the title compound, 2-(2-(4-((3,4-dihydro-4-oxo-3-arylquinazolin-2-yl)methyl)piperazin-1-yl) acetoyloxy)-2-phenyl acetic acid esters (1). The structures of all the new compounds obtained in the present work are supported by spectral and analytical data.     

One-Pot Synthesis of Dialkyl Succinates Containing an α -Amino Group and a β-Ylide Moiety Using Electron-Deficient Acetylenic Esters

The new succinic esters containing an α -amino group and a β -ylide moiety have been prepared in excellent yields by the three-components approach starting with the commercially available activated acetylenic esters and 2-aminothiazole or 4,5-dihydrothiazole-2-thiol in the presence of trivalent phosphine.     

Poly-α-n-alkyl Acrylic Derivatives: Synthesis,Influence of Molecuur Weight and n-Alkyl Group Length on Physical and Physicochemical Properties

Abstract

A series of α-n-alkyl acrylic acid monomers was synthesized and homopolymerized by a radical route. Methylation of polyacids using diazomethane led to the corresponding methyl esters and allowed physicochemical analysis. The thermal stability of polyacids and polymethyl esters is insensitive to the nature of the alkyl group and to the molecular weight. The glass transition temperature, T _g, classically decreases with increases in alkyl group length such as alkyl polymethacrylates. Molecular weight has a drastic influence on T _g for short alkyl groups.     

Synthesis and carbene decomposition of functionally substituted diazoacetate esters. 6. Propargyl diazoacetate

A synthesis of propargyl diazoacetate (I) was carried out and its chemical transformations were studied. The reaction of (I) in the presence of Rh(OAc)₂ at 25C with 1-pentyne gives the propargyl ester of l-propylcyclopropene-3-carboxylic acid in 80% yield, while reaction with 2,3-dimethyl-2-butene at 60C results in the propargyl ester of tetramethylcyclopropanecarboxylic acid in 10% yield. Compound (I) reacts under the same conditions (35–60C) with ether, CH₂Cl₂ and water, with the formation of propargyl esters of ethoxyacetic, 2,3-dichloropropionic, and a mixture of glycols and 2-[(propyn-2-yl)-oxycarbonyl]methoxy acetic acids in yields of up to 35%. A spontaneous oligomerization of (I) was observed as a result of a dipolar [1, 3]-cycloaddition of the CH=N₂ fragment of one molecule of (I) to the terminal triple bond of the second molecule with the formation of oligomers of 3-hydroxymethylpyrazole-5-carboxylic acid.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1051–1056, May, 1991.     

Synthesis of Di- and Triterpenoid Ferrocenyltriazoles

Ferrocene conjugates with a lupane triterpenoid linked through a triazole ring and C₃ or C₆ hydrocarbon tether were synthesized by reaction of ferrocenylalkylazides with betulonic acid propargyl ester. Analogous conjugates were obtained from dehydroabietic acid propargyl ester.     

Regioselective synthesis of pyrrolin-3-ones and 2,3,4,5-tetrahydro[1,3]-oxazines from N-vinylic amidines

Achiral and optically active N-vinylic amidines are obtained by simple addition of amidines to acetylenic esters. Thermal intramolecular cyclization of these substrates containing a carboxylate group in position 3 gives pyrrolin-3-ones. The enaminone character of these compounds towards propargyl bromide, diethyl azodicarboxylate, diethyl acetylenedicarboxylate, ethyl propiolate and phenyl isocyanate is studied and functionalized pyrrolin-3-one derivatives are obtained. The reaction of the pyrrolinones prepared with diethyl ketomalonate leads to new 1,3-oxazine derivatives.     

Substituent Effects on Oxidation‐Induced Formation of Quinone Methides from Arylboronic Ester Precursors

A series of arylboronic esters containing different aromatic substituents and various benzylic leaving groups (Br or N⁺Me₃Br^?) have been synthesized. The substituent effects on their reactivity with H₂O₂ and formation of quinone methide (QM) have been investigated. NMR spectroscopy and ethyl vinyl ether (EVE) trapping experiments were used to determine the reaction mechanism and QM formation, respectively. QMs were not generated during oxidative cleavage of the boronic esters but by subsequent transformation of the phenol products under physiological conditions. The oxidative deboronation is facilitated by electron‐withdrawing substituents, such as aromatic F, NO₂, or benzylic N⁺Me₃Br^?, whereas electron‐donating substituents or a better leaving group favor QM generation. Compounds containing an aromatic CH₃ or OMe group, or a good leaving group (Br), efficiently generate QMs under physiological conditions. Finally, a quantitative relationship between the structure and activity has been established for the arylboronic esters by using a Hammett plot. The reactivity of the arylboronic acids/esters and the inhibition or facilitation of QM formation can now be predictably adjusted. This adjustment is important as some applications may benefit and others may be limited by QM generation.     

Unexpected Rearrangement in the Reaction of 7‐Mercapto‐4‐methylcoumarin with 1‐Mono‐ and 1,1‐Dimethyl Propargyl Alcohols

The reaction of 7‐mercapto‐4‐methylcoumarin (4) with 1‐mono‐ and 1,1‐dimethyl propargyl alcohols in H₃PO₄ afforded the corresponding β‐(7‐coumarinthio)ketones with a rearrangement of the carbon chain of propargyl. A possible mechanism of this rearrangement was proposed.     

Synthesis and characterization of hyperbranched polystyrene via click reaction of AB2 macromonomer

Well‐defined hyperbranched polystyrenes have been successfully prepared by polymerization of AB₂ macromonomer, polystyrene containing an azide group at its one end and two terminal propargyl groups at the other end via click reaction. For preparation of AB₂ macromonomers, an ATRP initiator, bispropargyl 2‐bromosuccinate (BPBS) with two propargyl groups and one bromine group was synthesized by the successive bromination and esterification reaction of L ‐aspartic acid. The resulting BPBS initiated the ATRP of St, and subsequently, the terminal bromine groups of (CH≡C)₂‐PS‐Brs were substituted by N₃ via the reaction with sodium azide resulting the AB₂ macromonomer, (CH≡C)₂‐PS‐N₃ with various molecular weights. All intermediates and the resultant polymers were characterized by GPC, ¹H NMR, FTIR, and MALLS methods. The polymerization kinetics study showed fast increase of DP at the initial stage of polymerization and then slow increase of their DP. The final “HyperMacs” have high‐molecular weight up to M_w,MALLS = 340,000 g/mol, their molecular weight distributions were moderately narrow (M_w/M_n = 1.47–1.65). The ratios of [η]_H/[η]_L of the HyperMacs formed in the polymerization system increased with evolution of polymerization. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 454–462, 2010