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Research has been conducted on the preparation of the conformationally restricted nicotinoid from D- and L-glutamic acid. The pyroglutamic acid derivative coupling with ortho-lithiated 4-chloropyridine is described.

1,3,5-Triazinanes, as a kind of versatile building block, are applied in the synthesis of chromeno[2,3- d ]pyrimidin-5-one derivatives via two different reaction modes, which perfectly exhibits the powerful function of 1,3,5-triazinane as a three-atom synthon along with the structure variation of another substrate. The two annulation reactions proceed under mild conditions and bear broad substrate scope and high yield.

A microwave-promoted multicomponent reaction of 3-formylchromones, amines, and paraformaldehyde was achieved under catalyst-free and solvent-free conditions, delivering 5 H -chromeno[2,3- d ]pyrimidin-5-one derivatives in good to excellent yields via an unexpected annulation pathway, which further expanded the synthetic application of paraformaldehyde as a C1 building block.

We have developed cobalt-catalyzed, bidentate 2-(1-methylhydrazinyl)pyridine (MHP)-directed C( sp 2 )-H alkylation/annulation of benzoic hydrazides with various alkenes. Notably, diverse cyclopenta[ c ]isoquinolinones and dihydroisoquinolinones were obtained via this functional group-tolerant protocol. The reaction can be performed on a gram scale while maintaining an excellent yield, and the directing group can be removed efficiently under mild conditions. Furthermore, density-functional theory (DFT) calculations provide an incisive understanding of the observed regioselectivities for different olefins.

Palladium-catalyzed C(sp 2 )-H arylation of ortho C-H bonds involving 2-(1-methylhydrazinyl)pyridine (MHP) as the directing group has been investigated. The reaction proceeds smoothly under an air atmosphere to generate biaryl derivatives in an environmentally friendly manner while tolerating a wide range of functional groups. Notably, the directing group present in the product could be easily removed under mild reductive conditions., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

The synthesis of 3,4-dihydro-2 H -1,3-thiazines from α-enolic dithioesters and 1,3,5-triazinanes has been achieved via a formal (3 + 3) annulation reaction under thermal conditions, where 1,3,5-triazinanes were utilized as three-atom synthons. This transformation is catalyst-free and additive-free.

In this study, BaCe 0.9 Er 0.1 O 3-α was synthesized by a microemulsion method. Then, a BaCe 0.9 Er 0.1 O 3-α -K 2 SO 4 -BaSO 4 composite electrolyte was obtained by compounding it with a K 2 SO 4 -Li 2 SO 4 solid solution. BaCe 0.9 Er 0.1 O 3-α and BaCe 0.9 Er 0.1 O 3-α -K 2 SO 4 -BaSO 4 were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectrometry. AC impedance spectroscopy was measured in a nitrogen atmosphere at 400-700 °C. The logσ~log ( p O 2 ) curves and fuel cell performances of BaCe 0.9 Er 0.1 O 3-α and BaCe 0.9 Er 0.1 O 3-α -K 2 SO 4 -BaSO 4 were tested at 700 °C. The maximum output power density of BaCe 0.9 Er 0.1 O 3-α -K 2 SO 4 -BaSO 4 was 115.9 mW·cm -2 at 700 °C, which is ten times higher than that of BaCe 0.9 Er 0.1 O 3-α .

(+)-Mintlactone, a bicyclic monoterpene natural product, has been efficiently assembled from (-)-citronellol in three steps. The synthesis features nitrous acid-induced formal isopropylidene "demethanation" and the molybdenum-mediated intramolecular hetero-Pauson-Khand reaction.

An asymmetric total synthesis of (-)-5,6-dihydrocineromycin B has been accomplished in 13 steps from (-)-linalool O-triethylsilyl ether or 12 steps from geraniol. The present synthesis features (i) an intermolecular Wittig reaction involving an aldehyde possessing a ketophosphonate functionality and (ii) an intramolecular Horner-Wadsworth-Emmons olefination.

The first total synthesis of (+/-)-subincanadine F, a bioactive indole alkaloid structurally featuring a 1-azabicyclo[4.3.1]decane unit, has been realized from 1-(para-methoxybenzyl)tryptamine in six steps. The bridge-containing tetracyclic framework of subincanadine F was efficiently assembled by a SmI2-mediated ring opening followed by an acid-mediated Mannich reaction. In addition, the tetracyclic ketoester 6, a key intermediate potentially useful for synthesizing structurally related indole alkaloids as well, was obtained in one step from alpha,beta-diketoester 5.

We have described a concise construction of the pentacyclic benz[f]indolo[2,3-a]quinolizidine intermediate 3 (with an overall yield of 54% for three steps), featuring a tandem intermolecular formal aza-[3 + 3] cycloaddition/Pictet-Spengler cyclization. The present work can be considered as a formal synthesis of beta-carboline alkaloid (+/-)-tangutorine. Our strategy disclosed herein constitutes a new effective general synthetic approach toward the indoloquinolizidine family of alkaloids.

8O-methylaphanorphine was synthesized from 4-methoxyphenylacetaldehyde in 36% overall yield and in nine steps, featuring the formation of ring B via a Friedel-Crafts alkylative cyclization with the concomitant stereospecific introduction of the benzylic quaternary carbon center. The current work constitutes an efficient enantioselective formal synthesis of 3-benzazepine marine alkaloid (-)-aphanorphine.