Synthesis of Dicarboxylic Acids Comprising an Ether Linkage and Cyclic Skeleton and Its Further Application for High-Performance Aluminum Electrolyte Capacitors.

Aluminum electrolytic capacitors are essential components in all electronic devices, and it is known that their longevity depends on the performance of their electrolytes. We synthesized dicarboxylic acids having ether bonds showing the good solubility in ethylene glycol as a solvent and simultaneously developed a complete halogen removal method, which is strictly prohibited in capacitors. Moreover, the incorporation of bulky α-substituents and cyclic structures dramatically improved their heat resistance and can withstand high voltage, i.e., 764 V.

Highly Selective Synthesis of α-Aminoamide Utilizing an Umpolung Reaction and Characteristics of α-Hydrazonoester.

An umpolung reaction with α-hydrazonoesters was investigated, and it was found that α-N,N-dialkylaminoamides could be directly synthesized in yields up to 92% via a concomitant rearrangement of dialkylamino groups. As an application, a short synthesis of an inhibitor of glycine type-1-transporter was accomplished via subsequent functional group transformations in 28% overall yield.

Regulate Phosphorus Configuration in High P-Doped Hard Carbon as a Superanode for Sodium Storage.

Heteroatom-doped hard carbon is a popular method to optimize the electrochemical performance of anode electrodes for sodium-ion batteries. Herein, phosphorus-doped hollow carbon nanorods (P-HCNs) are obtained by a one-step synthesis with a high phosphorus content of 7.5 atom %. By controlling the P configuration, the P-HCNs03 exhibits reversible capacity as high as 260 mA h g-1 at the current density of 1.0 A g-1 after 500 cycles with an initial Coulombic efficiency (ICE) of 73%. When the amount of phosphorus in the as-prepared materials is changed, the different structures of the P-doped carbon lattices are analyzed by X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Based on the first-principles calculation, although the P-O bond has the most configurations, the excellent reversible capacity of the electrode is attributed to the strong Na-absorption ability of P═O and P-C bonds. The sodium-based dual-ion batteries (NDIBs) assembled with P-HCNs03 as an anode and expanded graphite as a cathode (P-HCNs03//EG) exhibited a high energy density of 138 W h kg-1 at a power density of 159 W kg-1. The results provide an important angle to optimize the performance of hard carbons with other functionalized heteroatoms.

Preparation of α-Perfluoroalkyl Ketones from α,ß-Unsaturated Ketones via Formal Hydroperfluoroalkylation.

Formal hydroperfluoroalkylation of enones is achieved in a two-step process comprising conjugate hydroboration and subsequent radical perfluoroalkylation. The 1,4-hydroboration of the enone is conducted in the absence of any transition metal catalyst with catecholborane in 1,2-dichloroethane, and the generated boron enolate is in situ α-perfluoroalkylated with a perfluoroalkyl iodide upon blue LED irradiation in the presence of an amine additive. Both reactions proceed under very mild conditions at room temperature.

2,3-Dimethoxy-2,3-dimethyl-1,4-dioxane as a useful precursor to 2,3-dimethylene-1,4-dioxane for [4+2] cycloaddition reaction.

2,3-Dimethoxy-2,3-dimethyl-1,4-dioxane readily prepared from biacetyl serves as a stable precursor to 2,3-dimethylene-1,4-dioxane which undergoes a [4+2] cycloaddition reaction with dienophiles to give functionalized cyclohexene derivatives. The cycloaddition adducts obtained by the present procedure are transformed into potentially useful intermediates for biologically important materials.

N-Alkylation/aldol reaction of α-aldimino thioesters: a facile three-component coupling reaction.

Theoretical calculation of the reactivity of α-imino thioesters indicates that they are very reactive substrates for Umpolung N-alkylation. In fact, treatment of α-aldimino thioesters with dialkylzinc reagents in the presence of aldehydes or imines gives three-component coupling products in good yields.

Synthesis of Tetramic Acid Derivatives via a Tandem Umpolung Alkylation/Reduction/Cyclization Reaction of γ-Hydrazono ß-Ketoester.

An efficient method for the one-pot synthesis of tetramic acid derivatives was developed utilizing tandem umpolung N-alkylation/reduction/cyclization of γ-hydrazono ß-ketoester. By using this reaction as a key step, the total synthesis of the 3-spiro 7-hydroxamic acid tetralin which possesses an HDAC inhibitory activity was also achieved.

An umpolung reaction of α-iminothioesters possessing a cyclopropyl group.

An umpolung N-alkylation reaction of α-cyclopropyl α-iminothioesters with diethylaluminum chloride or ethylmagnesium bromide affords the corresponding N-ethylated α-aminothioesters in good yields. Subsequent oxidation and reaction of the N-ethylated product with a thiolate or a chloride anion proceed effectively to give the ring-opened products in good yields. In contrast, relatively "hard" nucleophiles did not give the ring-opened products but gave the addition products to the iminium carbon.

Preparation and facile addition reactions of iminium salts derived from amino ketene silyl acetal and amino silyl enol ether.

While iminium salts generated by the oxidation of amino ketene silyl acetals show intriguing reactivities to give useful γ-oxo-α-amino esters via reactions with silyl enol ethers in good yields, new iminium salts are also prepared by the oxidation of amino silyl enol ethers. They undergo facile addition reaction with various nucleophiles to give α-amino ketone derivatives in good yields.

Tandem N, N-Dialkylation Reaction of N-Trimethylsilyl α-Iminoesters Utilizing an Umpolung Reaction and Characteristics of the Silyl Substituent: Synthesis of Pyrrolidine, Piperidine, and Iminodiacetate.

Umpolung reactions of N-trimethylsilyl α-iminoester with organometallics gave directly N-alkylaminoesters in high yields without the need for removing a protecting group at the nitrogen atom. Efficient syntheses of pyrrolidines, piperidines, and iminodiacetate derivatives were also developed via tandem N,N- or N, C-dialkylation reactions utilizing characteristics of the silyl substituent. Furthermore, under the influence of silica gel, the addition of an enolate to the imino nitrogen proceeded to give an iminodiacetate derivative.

Double nucleophilic addition to iminomalonate, leading to the synthesis of quaternary α-amino diesters and desymmetrization of the products.

Alkylation of iminomalonate with Grignard reagents followed by oxidation and allylation gave symmetrical quaternary α-amino diesters in good yields. Subsequent desymmetrization of a diol derivative from these products was conducted via asymmetric carbamylation catalyzed by Cu-Bnbox to give chiral quaternary aminodiol mono-carbamates.

A facile approach to 2-alkoxyindolin-3-one and its application to the synthesis of N-benzyl matemone.

2-Alkoxycarbonylindolin-3-one is synthesized from a methoxyglycine derivative via a 1,2-aza-Brook rearrangement followed by cyclization with bis(trimethylsilyl)aluminum chloride. A short-step synthesis of N-benzyl matemone is successfully carried out using the present indolin-3-one synthesis.

Umpolung Reaction of α-Imino Thioesters and the Subsequent C-C Bond Formation with the Unexpected Alkylthio Rearrangement.

An umpolung reaction of the α-imino thioester was examined, and we found that α-imino thioesters were more effective substrates for the umpolung N-alkylation than conventional α-imino esters and they gave N-alkylated amino thioesters in high yields under mild reaction conditions in a short time. A new type of C-C bond formation followed by an unexpected rearrangement of the alkylthio group took place with the unsaturated ketones to afford the ß-alkylthio-α-amino thioesters in high yields with good diastereoselectivity.

Umpolung Reactions of α-Imino Esters: Useful Methods for the Preparation of α-Amino Acid Frameworks.

This paper summarizes our recent efforts toward the development of tandem reactions utilizing umpolung reactions of α-imino esters. A highly diastereoselective tandem N-alkylation-Mannich reaction of α-imino esters was developed. A tandem N-alkylation-addition reaction of α-imino esters derived from ethyl glyoxylate with various aldehydes proceeded to give 1,2-amino alcohols. The same reaction also proceeded efficiently using a novel flow system comprising two connected microreactors. Novel syntheses of α-quaternary alkynyl amino esters and allenoates were developed through the use of umpolung N-addition to ß,γ-alkynyl α-imino esters, followed by regioselective acylation. In addition, a highly regioselective tandem N-alkylation-vinylogous aldol reaction of ß,γ-alkenyl α-imino esters was discovered. N-Alkylation of α-iminophosphonates followed by a Horner-Wadsworth-Emmons reaction with aldehydes occurred to afford enamines, which can be used in a four-component coupling reaction with methyl vinyl ketone. α-N-Acyloxyimino esters served as highly efficient substrates for the N,N,C-trialkylation reaction to introduce various nucleophiles at the imino nitrogen and carbon atoms.

Tandem N-alkylation/vinylogous aldol reaction of ß,γ-alkenyl α-iminoester.

This report describes a highly regioselective tandem N-alkylation/vinylogous aldol reaction of ß,γ-alkenyl α-iminoesters. The sulfur group improves the regioselectivity of the directed vinylogous aldol reaction, providing a new synthetic method of 3-amino-2-pyrones.

Regioselective tandem N-alkylation/C-acylation of ß,γ-alkynyl α-imino esters.

A new synthesis of α-quaternary alkynyl amino esters and allenoates was developed utilizing umpolung N-addition to ß,γ-alkynyl α-imino esters followed by regioselective acylation. The reaction exhibits broad substrate generality and unique regioselectivity. Moreover, synthesis of α-quaternary alkynyl amino esters was also carried out via oxidation of the intermediary enolate followed by alkylation.

Use of N-allylidene-1,1-diphenylethanamine as a latent acrolein synthon in the double nucleophilic addition reaction of ketene silyl (Thio)acetals and allylborolanes.

In the presence of silica gel and water, a mixture of ketene silyl acetals and 2-allyl-4,4,5,5-tetramethyl-1,3,2-dioxaborolane underwent 1,4- and subsequently 1,2-addition with N-allylidene-1,1-diphenylethanamine to give delta-hydroxyesters in good yields, where the allylideneamine was successfully used as an acrolein equivalent.

Conjugated imines and iminium salts as versatile acceptors of nucleophiles.

Growing interests in nitrogen-containing molecules involving bioactive and functional materials have stimulated the recent development of synthetic methodologies where nucleophilic addition reactions to imino carbons are utilized in crucial steps. This article summarizes double nucleophilic addition reactions with alpha,beta-unsaturated aldimines, addition reactions using alkynyl imines, "umpoled" reactions of alpha-imino esters, and the use of iminium salts as reactive electrophiles.

Synthesis of N-allylideneamines and their use for the double nucleophilic addition of ketene silyl (thio)acetals and trimethylsilyl cyanide.

N-Allylideneamines 1a, b were prepared from acrolein and diphenylethyl or trityl amine in the presence of Ti(OEt)4. Double nucleophilic addition of various ketene silyl (thio)acetals and trimethylsilyl cyanide to these imines proceeded efficiently to give, after workup with TFA, homoglutamic acid derivatives 3 and valerolactam 5.