利用一个通用的方法全合成Fuscinarin和Fuscins

通过一个共同的中间体6,首次全合成了fuscinarin (1)和全合成了fuscins,它们都是戊烯酮(pentaketide)的代谢物,在亲近闪烁检测(scintillation proximity assay)中显示具有抗CCR5的活性。这一合成主要是利用微波辅助的 ortho-Claisen/Cope 重排的串联反应更合成中间体10。     

Application of the Novel Tandem Process Diels‐Alder Reaction/Ireland‐Claisen Rearrangement to the Synthesis of rac‐Juvabione and rac‐Epijuvabione

The novel tandem process Diels‐Alder reaction/Ireland‐Claisen rearrangement shows a high diastereoselectivity for the Ireland‐Claisen rearrangement starting from the endo‐product of the Diels‐Alder reaction. Based on this mechanistic knowledge, the novel tandem process could be applied to the synthesis of rac‐juvabione.     

Gold/Acid‐Co‐catalyzed Direct Microwave‐Assisted Synthesis of Fused Azaheterocycles from Propargylic Hydroperoxides

The gold–acid‐co‐catalyzed synthesis of nine series of fused azaheterocycles with structural diversity starting from the same synthons as readily available propargylic hydroperoxides and aromatic amines has been achieved. The overall tandem process consists in a gold‐catalyzed hydroperoxide rearrangement/Michael reaction followed by a final acid‐catalyzed cyclization.     

通过三乙基铝促进的a-羟基环氧化合物的重排还原反应合成Madindoline母核片断——全取代环戊烯二酮单元

The fully substituted cyclopentenedione core of madindoline A （1） and B （2） as potent and selective inhibitor of IL-6 has been synthesized efficiently. The quaternary carbon center C-2＇ was constructed on the basis of a newly developed AIEt3-promoted tandem reductive rearrangement of α-hydroxy epoxides.     

Visible‐Light‐Mediated Photocatalytic Difunctionalization of Olefins by Radical Acylarylation and Tandem Acylation/Semipinacol Rearrangement

A novel method for the mild photoredox‐mediated tandem radical acylarylation and tandem acylation/semipinacol rearrangement has been developed. The synthesis of highly functionalized ketones bearing all‐carbon α‐ or β‐quaternary centers has been achieved using easily available symmetric aromatic carboxylic anhydrides as the acyl radical source. The method allows for a straightforward introduction of the keto functionality and concomitant construction of molecular complexity in a single operation.     

Extensive Studies on the AIEt3／THF-Promoted Diastereoselective Tandem Rearrangement／Reduction of a-Hydroxy （Amino） Heterocyclopropane： An Efficient Approach to 2-Quaternary 1,3-Diheteroatom Units

A facile and highly diastereoselective method for the construction of 2-quaternary 1,3-amino alcohols and 1,3-diols has been developed on the basis of the AlEt3/THF-promoted tandem rearrangement/reductive reaction of α-hydroxy (amino) aziridines (epoxides). The progressive achievement in this article included that both 2-epimers of the units could be constructed from the initially same substrate. Also a stereochemistry assignment we reported previously was corrected.     

Highly efficient transfer of chirality from macrocyclic conformation in the tandem oxy-Cope/Claisen/ene reaction

We report three highly stereoselective pericyclic reactions occurring in cascade leading to the synthesis of Decalins skeletons possessing two contiguous quaternary centers. The tandem reaction is triggered by an oxy-Cope rearrangement to create in situ a 10-membered ring enol ether macrocyle 6, which immediately rearranges via a Claisen [3,3] shift to the corresponding E-cyclodec-6-en-1-one 7. The latter spontaneously cyclizes via a transannular ene reaction to produce Decalin 5. Analysis of the mechanism with respect to the origin of the high diastereoselectivity of the tandem oxy-Cope/Claisen/ene reaction is presented.     

An Oxidative Rearrangement of 6‐Phenylbicyclo[3.2.0]heptan‐6‐ol to 1,1′‐Biphenyl‐Carbaldehydes: A Mechanistic Study

Acid‐catalyzed rearrangement of 6‐phenylbicyclo[3.2.0]heptan‐6‐ol gave 1,1′‐biphenyl and 1,1′‐biphenyl‐carbaldehydes in small amounts as well as the expected rearrangement products. A detailed study of the reaction mechanism revealed that the conversion occurs via an oxidative process through the consecutive formation of cycloheptadienes, cycloheptatrienes, and 1,1′‐biphenyls. The acid‐catalyzed rearrangement of 6‐phenylbicyclo[3.2.0]hept‐2‐en‐6‐ols gave 1‐ and 2‐phenylcycloheptatrienes directly, from which 1,1′‐biphenyl and 1,1′‐biphenyl‐carbaldehydes were obtained by oxidation.     

Multicomponent Double Diels–Alder/Nazarov Tandem Cyclization of Symmetric Cross‐Conjugated Diynones to Generate [6‐5‐6] Tricyclic Products

The construction of complex polycyclic terpenoid products in an efficient and step‐economical manner using multicomponent and tandem processes is highly valuable. Herein, we report a tandem cyclization sequence that initiates with a multicomponent double Diels–Alder reaction of cross‐conjugated diynones, followed by a Nazarov cyclization to efficiently produce [6‐5‐6] tricyclic products with excellent regio‐ and diastereoselectivity. This methodology generates five new carbon–carbon bonds, three rings, quaternary or vicinal quaternary carbons, and stereogenic centers in a one‐pot reaction.     

Efficient Synthesis of Spirooxindole Pyrrolones by a Rhodium(III)‐Catalyzed C−H Activation/Carbene Insertion/Lossen Rearrangement Sequence

A rhodium(III)‐catalyzed domino annulation of simple olefins with diazo oxindoles to give spirooxindole pyrrolone products is described. This reaction can be formally viewed as the result of an anomalous tandem C?H activation, carbene insertion, Lossen rearrangement, and a nucleophilic addition process. The potential utility of this reaction was further demonstrated by the late‐stage diversification of drug molecules.     

Complexity-enhancing acid-promoted rearrangement of tricyclic products of tandem Ugi 4CC/intramolecular Diels-Alder reaction

The unexpected rearrangement of 2,3,7,7a-tetrahydro-3a,6-epoxyisoindol-1-one products of the tandem Ugi 4CC/intramolecular Diels-Alder reaction in 85% H3PO4 was discovered to provide diastereomerically pure tricyclic bislactam lactone-containing natural product-like products in high yield. Mechanistic rationale for the observed rearrangement was proposed and has been tentatively confirmed by additional experiments.     

Tandem Anionic oxy‐Cope Rearrangement/Oxygenation Reactions as a Versatile Method for Approaching Diverse Scaffolds

Tandem anionic oxy‐Cope rearrangement/radical oxygenation reactions provide δ,?‐unsaturated α‐(aminoxy) carbonyl compounds, which serve as convenient precursors to diverse compound classes. Functionalized carbocycles are accessible by very rare all‐carbon 5‐endo‐trig cyclizations, but also common 5‐exo‐trig radical cyclizations, based on the persistent radical effect. The tandem reactions can be further extended by highly diastereoselective allylation or reduction steps to give complex scaffolds.     

Rhodium carboxylate catalyzed decomposition of vinyldiazoacetates in the presence of heterodienes: enantioselective synthesis of the 6-azabicyclo[3.2.2]nonane and 6-azabicyclo[3.2.2]nonanone ring systems

Dirhodium tetracarboxylate catalyzed decomposition of vinyldiazoacetates in the presence of N-phenoxycarbonyl protected 1,2-dihydropyridines or 1-methyl-2-pyridones is a direct method for the construction of the 6-azabicyclo[3.2.2]nonane ring system. The [3 + 4] cycloaddition occurs by a tandem cyclopropanation/Cope rearrangement. Asymmetric induction is possible in these transformations either by using (S)-lactate methyl ester as a chiral auxiliary or dirhodium tetraprolinates as chiral catalysts.     

Total Synthesis of (−)‐Merochlorin A

The first asymmetric total synthesis of the meroterpenoid (?)‐merochlorin A is described. The route features enantiospecific gold‐catalyzed tandem 1,3‐acyloxy migration/Nazarov/aldol reaction sequence to furnish the bicyclo[3.3.0]octane core in a single step from a linear propargylic 1,3‐enyne aldehyde. After completion of the central skeleton by reductive enol lactone rearrangement, late stage Diels–Alder cycloaddition/aromatization sequence installed the resorcinol. An additional salient feature of the synthesis is the assignment of the absolute configuration, which had not been determined previously.     

Catalytic Enantioselective Synthesis of 2,5‐Dihydrooxepines

A Michael addition initiated cyclopropanation/retro‐Claisen rearrangement tandem reaction was developed for the enantioselective synthesis of highly functionalized 2,5‐dihydrooxepines. In the presence of a chiral oxazaborolidinium ion (COBI) catalyst, the reaction proceeds to give good yields and high enantioselectivity.     

Studies on Amine Oxide Rearrangement: Synthesis of Pyrrolo[3,2‐c][1]benzothiopyran‐4‐one

A methodology, based on tandem [2,3] and [3,3] sigmatropic rearrangement, has been described for the synthesis of hitherto unreported, potentially bioactive pyrrolo[3,2‐c][1]benzothiopyran‐4‐ones (6a–g) derivatives.     

Chemical Consequences of the Mechanical Bond: A Tandem Active Template‐Rearrangement Reaction

We report the unexpected discovery of a tandem active template CuAAC‐rearrangement process, in which N₂ is extruded on the way to the 1,2,3‐triazole product to give instead acrylamide rotaxanes. Mechanistic investigations suggest this process is dictated by the mechanical bond, which stabilizes the Cu^I‐triazolide intermediate of the CuAAC reaction and diverts it down the rearrangement pathway; when no mechanical bond is formed, the CuAAC product is isolated.     

Synthesis of 2,4,6‐trisubstituted naphthalenes via novel copper‐promoted tandem coupling and intramolecular cyclization

An unprecedented copper‐promoted tandem coupling and intramolecular cyclization reaction is disclosed. This strategy offers a simple and promising method for accessing 2,4,6‐trisubstituted naphthalenes. A reaction mechanism involving initial formation of diynes followed by a 6‐exo‐dig cyclization and subsequent rearrangement is proposed. Copyright © 2009 John Wiley & Sons, Ltd.     

Mass spectrometric properties of N‐(2‐methoxybenzyl)‐2‐(2,4,6‐trimethoxyphenyl)ethanamine (2,4,6‐TMPEA‐NBOMe), a new representative of designer drugs of NBOMe series and derivatives thereof

Emergence of new psychoactive substances, hallucinogenic phenethylamines in particular, in illicit market is a serious threat to human health in global scale. We have detected and identified N‐(2‐methoxybenzyl)‐2‐(2,4,6‐trimethoxyphenyl)ethanamine (2,4,6‐TMPEA‐NBOMe), a new compound in NBOMe series. Identification was achieved by means of gas chromatography/mass spectrometry (GC/MS), including high‐resolution mass spectrometry with tandem experiments (GC/HRMS and GC/HRMS²), ultra‐high performance liquid chromatography/high‐resolution mass spectrometry with tandem experiments (UHPLC/HRMS and UHPLC/HRMS²), and ¹H and ¹³C nuclear magnetic resonance spectroscopy. The peculiarities of fragmentation of the compound under electron ionization (EI) and collision‐induced dissociation were studied. Despite of the empirical rule denying migration of the hydrogen atom in McLafferty rearrangement to the benzene ring with substituents in the both ortho‐positions, it easily occurs for 2,4,6‐TMPEA‐NBOMe in EI conditions. We have noticed that electron‐donating substituents, e.g. methoxy groups in the both ortho‐positions and para‐positions favor the rearrangement. For specially synthesized N‐methyl and N‐acyl derivatives McLafferty rearrangement is not observed. N‐Acyl derivatives demonstrate McLafferty rearrangement, but the charge retains at the alternative fragment involving N‐acyl carbonyl group. We have also showed that the hydrogen atoms in 2,4,6‐trimethoxybenzene ring may be easily substituted for deuterium or for strong electrophiles like trifluoroacetyl. Analytical characteristics of 2,4,6‐TMPEA‐NBOMe and of some derivatives thereof which enable their determination in various criminal seizures are given. Copyright © 2016 John Wiley & Sons, Ltd.     

A one-pot, reductive amination/6-endo-trig cyclisation for the stereoselective synthesis of 6-substituted-4-oxopipecolic acids

The first stereoselective synthesis of 2,6-trans-6-substituted-4-oxo-L-pipecolic acids using a tandem reductive amination/6-endo-trig cyclisation process is described. The sequential reduction and cyclisation mediated by sodium cyanoborohydride allowed the preparation of a series of highly functionalised 6-alkyl and 6-aryl analogues.