A New Synthesis of α-Fluoromalonates from α-Fluoro-α-phosphonyl Malonates Using P-C Bond Cleavage

P-C bond cleavage of α-fluoro-α-phosphonyl malonates using magnesium chloride provides a new synthetic route to α-fluoro malonates.     

Determination of isoflavone glucoside malonates in Trifolium pratense L. (red clover) extracts: quantification and stability studies.

Isoflavones, their glucosides and their glucoside malonates were determined in red clover leaf extracts using reversed-phase LC coupled to atmospheric pressure chemical ionisation mass spectrometry (APCI-MS), UV and fluorescence detectors and the stability of the malonates was investigated. Extracts can be stored at least 1-2 weeks at -20 degrees C without loss of malonates. In LC-separated fractions the malonates are most stable when stored at low temperature after evaporation to dryness. The concentrations of eight major isoflavones ranged from 0.04 to 5 mg/g leaves.     

5-单取代丙二酸亚异丙酯的简便合成法

5-单烃基取代的丙二酸亚异丙酯是重要的有机合成中间体^[1],由于它的活性亚甲基具有较强的酸性(pK_a=4.75),用卤代烃直接烃化时,往往生成5,5-双取代产物^[2,3],所以一般用间接方法合成5-单取代丙二酸亚异丙酯^[4～6],其中以丙二酸亚异丙酯与羰基化合物缩合成亚烃基丙二酸亚异丙酯,继而还原的两步法最为普遍,常用的还原方法和还原剂有催化氢化、氢化铝锂,硼氢化钠等^[6]。     

Enantioselective Michael reaction catalyzed by well-defined chiral ru amido complexes: isolation and characterization of the catalyst intermediate,ru malonato complex having a metal-carbon bond

Chiral Ru amido complexes promote asymmetric Michael addition of malonates to cyclic enones, leading to Michael adducts with excellent ee's, in which the chiral Ru amido complexes react with malonates to give isolable catalyst intermediates, chiral Ru malonato complexes bearing a metal bound C-nucleophile.     

Hemisynthesis of methyl pyrethroates from γ-alkoxy-alkylidene malonates and isopropylidenediphenylsulfurane and isopropylidenetriphenylphosphorane

Hemisynthesis of methyl pyrethroates from γ-alkoxy-alkylidene malonates and isopropylidenediphenylsulfurane and isopropylidenetriphenylphosphorane is disclosed. It takes advantage of the high degree of stereocontrol observed in the cyclopropanation of γ-alkoxy-alkylidene malonates by the above mentioned ylides.     

Palladium-catalyzed regiocontrolled and stereoselective alkylations of bis(trifluoroethyl) malonates with dienyl alcohols

The triethylborane-promoted and palladium-catalyzed reactions of 2,4-dienyl alcohols or the corresponding isomeric divinyl alcohols with bis(trifluoroethyl) malonates provide an improved method for the regio- and stereoselective dienylation of malonates. The phosphine ligand is an important control element in the reaction. Combinations of Pd(OAc)₂ with BIPHEP or BINAP give dienylated malonates in good yield and higher isomeric purity than the traditional combination of Pd(OAc)₂ and Ph₃P affords in the catalyzed reactions of dienyl acetates.     

Novel chiral thioureas for highly enantioselective Michael reactions of malonates to nitroalkenes

Highly efficient Michael addition reactions of malonates to nitroalkenes catalyzed by novel chiral thioureas derived from optically pure BINOL and amino acids are reported. Various trans-nitroalkenes reacted with malonates affording the desired products in up to 95% yield with excellent enantioselectivities (up to 97% ee).     

One-pot oxidative Mannich-type reaction of lactams with alkyl malonates

One-pot substitution of a C-H bond at the position next to the nitrogen atom of lactams with alkyl malonates proceeded effectively by dehydrogenation of lactams with N-tert-butylbenzenesulfinimidoyl chloride, followed by Mannich-type addition of alkyl malonates.     

Enantioselectively organocatalytic Michael addition of ketones to alkylidene malonates

An organocatalytic asymmetric Michael addition of ketones to alkylidene malonates has been developed. In the presence of 20 mol % of urea 1a or N-(pyrrolidin-2-ylmethyl)trifluoromethanesulfonamide 1j, the reactions of ketones with alkylidene malonates afford the desired Michael adducts in moderate to good yields with good to high enantioselectivities under mild conditions.     

Recherches en vue de la synthèse de barbiturates organostanniques

Triphenyl and tributyltin hydrides have been found to add to the terminal double bond of unsaturated ethyl malonates to give organotin substituted ethyl malonates. Attempted cyclisation of the latter into barbituric compounds failed.     

Thermal decomposition of bivalent transition metal malonates in various atmospheres

The thermal decomposition of the malonates of bivalent transition metals (Mn, Fe, Co, Ni, Cu and Zn) was investigated by mainly TG-DTA, X-ray diffraction analysis and evolved gas analysis in atmospheres of N₂, CO₂ and O₂ and in the air. It was shown that CO₂ has an inhibiting effect on the decomposition whereas O₂ and air have the accelerating effects on the basis of N₂. The decomposition of the salts investigated can be classified into three groups from solid decomposition products: Mn and Zn malonates gave the metal oxides including 1–1.5 moles of elementary carbon, while Cu and Ni malonates gave the metals with 1–1.5 moles of the carbon. Fe and Co malonates in the last group gave once the metal oxides with 1-0.5 moles of the carbon and the oxides produced were subsequently reduced to the metals by the carbon. A possible reaction mechanism for the malonates was discussed and compared with those of the corresponding oxalates and succinates.     

Synthesis of β‐Arylacyl/β‐Heteroarylacyl‐β‐alkylidene Malonates and Their Application in Substituted Pyridone Synthesis

A novel approach has been developed for the synthesis of β‐arylacyl/β‐heteroarylacyl‐β‐alkylidine malonates in moderate to good yields by the reaction of Stork aryl and heteroaryl enamine with β‐chloroalkylidene malonates. The reaction involves conjugate (Michael) addition of Stork enamine on β‐chloroalkylidene malonates and elimination of chloride ion. These Michael adducts were utilized as intermediates for the synthesis of highly substituted 1,4‐dialkyl‐2‐oxo‐6‐aryl/hetreoaryl‐1,2‐dihydro‐pyridine‐3‐carboxylic acid ethyl esters via 5 + 1 ring annulation protocol.     

Novel synthesis of dihydropyrans and 2,8-dioxabicylo[3.3.0]oct-3-enes using Mn(III)-based oxidative cyclization

The Mn(III)-based reaction of 1,1-disubstituted alkenes with 2-(2-oxoethyl)malonates and 3-acetylpentane-1,4-diones gave novel substituted dihydropyrans and 2,8-dioxabicyclo[3.3.0]oct-3-enes in good yields, respectively. These routes rely on the nucleophilic character of the carbonyl-oxygen atoms of the malonates and pentanediones used to obtain the products by a cycloaddition reaction or cycloaddition-tandem cyclization reactions.     

Phosphomolybdic acid: An efficient and reusable catalyst for the synthesis of ��-phosphono malonates

Phosphomolybdic acid (H₃PMo₁₂O₄₀) is an efficient and reusable catalyst for the synthesis of the phospha-Michael addition of phosphite esters with different types of ??,??-unsaturated malonates to produce a variety of ??-phosphono malonates.     

Asymmetric Michael Addition of Ketones to Alkylidene Malonates and Allylidene Malonates via Enamine-Metal Lewis Acid Bifunctional Catalysis

Novel enamine-metal Lewis acid bifunctional catalysts were successfully applied to the asymmetric Michael addition of ketones to alkylidene malonates, offering excellent stereoselectivity (up to >99% ee and >99:1 dr). The asymmetric Michael addition of ketones to allylidene malonates was also achieved.     

Synthesis of alkyl-1,3-dihydro-3-oxobenzo[<Emphasis Type="Italic">c</Emphasis>]oxepine-4-carboxylates

Alkyl-1,3-dihydro-3-oxobenzo[c]oxepine-4-carboxylates were obtained by bromination of dialkyl-2-(2-methylbenzylidene)malonates with N-bromosuccinimide followed by the cyclization of dialkyl-2-(2-bromomethylbenzylidene) malonates.     

Synthesis of highly symmetric mesomeric triazaphenalene betaines

The synthesis of seven mesomeric triazaphenalene betaines 4a‐g by condensation reaction of hexahydro‐2H‐pyrimido[1,2‐a]pyrimidine 1 with diethyl malonates 2a‐g or with bis(2,4,6‐trichlorophenyl)malonates 3c,f has been achieved. The guanidine 1 forms in benzene solution a salt with trimethyl methanetricarboxylate 5 which upon heating produces 4a.     

Dependence of enantioselectivity on the ligand/metal ratio in the asymmetric Michael addition of indole to benzylidene malonates: electronic influence of substrates

Simple bis(oxazoline) ligands, especially azabis(oxazolines), can promote the copper(II)-catalyzed Michael addition of indoles to benzylidene malonates with up to >99 % ee (ee=enantiomeric excess), provided that the ligand/metal ratio is tuned meticulously with particular regard to the electronic properties of the substrate. Despite a common paradigm followed in many asymmetric catalyses, an excess of chiral ligand is not always beneficial. In fact any excess of ligand has to be avoided to reach excellent enantioselectivities when electron-rich benzylidene malonates are used. On the contrary, malonates carrying an electron-withdrawing group require an excess of ligand for an optimum ee value. A correlation of optical yields versus the sigma(I) values of several para substituents shows a sigmoid trajectory. In the presence of an additive, such as triflate, the significance of the ligand/metal ratio vanishes and very good enantioselectivities are achieved at any rate--no matter whether electron-donating or withdrawing substituents are present.     

Solventless DBU-promoted Mannich-type reactions of α-amido p-tolylsulfones with diethyl fluoromalonates and diethyl malonates

Mannich-type reactions of α-amido p-tolylsulfones with diethyl fluoromalonates and diethyl malonates, respectively in presence of catalytic amount of DBU have been developed. A variety of α-amido p-tolylsulfones prepared from aromatic and aliphatic aldehydes reacts with diethyl fluoromalonates and diethyl malonates, respectively under mild reaction conditions to afford α-fluoro β-amino esters and β-amino esters in moderate to good yield.     

Palladium-catalyzed nucleophilic benzylic substitutions of benzylic esters

A palladium complex generated in situ from [Pd(eta3-C3H5)(cod)]BF4 and DPPF is a good catalyst for benzylic alkylation of benzyl methyl carbonate with the carbanion of dimethyl malonates. The catalytic reaction is applicable to a wide range of the benzylations of benzylic esters with malonates. The catalytic activity was heavily affected by the bite angle of the bidentate phosphine ligand on palladium. DPEphos ligand is superior to DPPF in the case of palladium-catalyzed benzylic amination of benzylic esters.