Corrected by: The Wieland-Miescher Ketone: A Journey from Organocatalysis to Natural Product SynthesisSynlett 2012; 2012(03): e2-e2DOI: 10.1055/s-0031-1290115

An unprecedented C-C coupling reaction between alkenes and ketones by hydrogen-atom transfer, using Fe(acac)3 PhSiH3 in EtOH, is described. This mild protocol features high site selectivity allows the construction of sterically congested structures containing tertiary alcohols quaternary centers. The overall process introduces a novel strategic bond disconnection for ring-closing reactions.

The first total synthesis of anominine has been achieved, and the absolute configuration product determined. key features include development a new, highly efficient organocatalyzed method for asymmetric Wieland−Miescher ketone building blocks, an unusual selenoxide [2,3]-sigmatropic rearrangement, ZrCl4-catalyzed indole coupling as well several chemoselective transformations controlled by structurally congested nature bicyclic core.

Abstract A highly efficient (93% overall yield) and enantioselective (94% ee ) synthesis of the Wieland–Miescher ketone (10‐g scale) through a solvent‐free Robinson annulation procedure is reported. The process involves only 1 mol% triethylamine as base in initial Michael organocatalyst N ‐tosyl‐( S )‐binam‐ L ‐prolinamide (2 mol%) benzoic acid (0.5 for intramolecular aldol process. This green protocol applied to wide range valuable building block analogues (10 examples). Among these,...

A concise synthesis of the Lycopodium alkaloid lycoposerramine Z is reported. Key to strategy a one-pot organocatalyzed Michael reaction followed by domino Robinson annulation/intramolecular aza-Michael promoted LiOH, leading enantiopure cis-decahydroquinolines.

This review highlights advances in the synthesis of morphan compoundsfrom 1980 to present day. 1 Introduction 2 Synthetic Approaches from Carbocyclic Compounds 2.1 Aminocyclization Processes Forming C(1)-NBond 2.1.1 From Amino Alkenes 2.1.2 Ketones 2.1.3 By Amine Alkylation 2.1.4 Conjugate Addition upon Enones 2.2 N-C(3)Bond 2.3 Cyclization C(3)-C(4) Bond 2.4 C(4)-C(5) 2.4.1 Aldol Reactions 2.4.2 Piperidine Ring Closure by a Heck Reaction 2.4.3 Alkenylation Enolates 2.4.4 Radical...

A methodology for the coupling of alkenes with aldehyde- or ketone-derived Cbz-hydrazones to form a new C–C bond through radical process is described. The sequence comprises an initial in situ generation putative iron hydride followed by hydrogen atom transfer alkene, hydrazone, and final reduction nitrogen-centered radical. Hydrogenation obtained hydrazines renders amines, including valuable tert-alkyl amines.

A general effective organocatalyzed synthesis of enantioenriched morphans with up to 92% ee was developed. The morphan scaffold constructed in a one-pot tandem asymmetric Michael addition followed by domino Robinson annulation/aza-Michael intramolecular reaction sequence from easily available starting materials.

The asymmetric total synthesis of the <italic>cis</italic>-phlegmarine alkaloid cermizine B was achieved rapidly and on a gram-scale by an uninterrupted eight-step sequence final reduction step.

The intermolecular reductive radical coupling of aldehydes with nonactivated alkenes, employing metal hydride atom transfer (MHAT) catalysis a combination FeII and FeIII salts, is described. This constitutes the first use as viable acceptor groups in MHAT reactions. insights gained this study led to reexamination previously reported intramolecular version reaction, addition salts allowed development more efficient second-generation approach.

Iron-catalyzed hydrogen atom transfer-mediated intermolecular C-C coupling reactions between alkenes and tosylhydrazones, followed by in situ cleavage of the tosylhydrazine intermediates using Et3N, are described. The process involves a new strategic bond disconnection resulting reductive alkylation nonactivated alkenes. reaction is operationally simple, proceeds under mild conditions, has wide substrate scope.

The use of isocyanides as acceptor groups in metal–hydride hydrogen atom transfer (MHAT) coupling reactions with nonactivated alkenes to form heterocycles is described. Monosubstituted couple and cyclize directly, whereas more substituted proceed via a two-step, one-pot procedure involving MHAT reductive cyclization followed by Minisci upon the addition acid. To highlight utility methodology, diverse variety such phenanthridines, indoles, isoquinolines were prepared.

This study aimed to determine the in vitro cytotoxicity and understand possible cytotoxic mechanisms via an silico of eleven chalcones synthesized from two acetophenones. Five were a prenylacetophenone isolated plant that grows Andean region Atacama Desert. The activity all was tested against breast cancer cell lines using MTT proliferation assay. results suggest prenyl group A-ring methoxy hydroxyl substituents B-ring appear be crucial for these compounds. 12 13 showed significant...

Abstract A diastereoselective synthesis of cis ‐5‐oxodecahydroquinolines is described in which three stereocenters are generated a one‐pot reaction. The reaction involves lithium hydroxide‐promoted Robinson annulation/intramolecular aza‐Michael domino process from an achiral acyclic tosylamine‐tethered β‐keto ester. development and scope this was facilitated through the use DFT‐based mechanistic studies, enabled observed diastereodivergent course azacyclization to be rationalized. varying...

A unified strategy for the synthesis of cis-phlegmarine group alkaloids is presented, leading to first serratezomine E (1) as well putative structure huperzine N (2). contrasteric hydrogenation method was developed based on use Wilkinson's catalyst, which allowed facial selectivity standard be completely overturned. Calculations were performed determine mechanism, and structures huperzines M are reassigned.

A highly congested decalin embodying an α-methylene ketone is synthesized in 11 steps from the Wieland–Miescher and efficiently converted to polycyclic frameworks of anominine tubingensin A, which constitutes first approach skeleton these indole diterpenoids.

A straightforward, two-step asymmetric synthesis of octahydroindoles has been developed on the basis two complementary strategies: (i) an organocatalyzed Michael reaction followed by a tandem Robinson-aza-Michael double cyclization catalyzed PS-BEMP, and (ii) diastereoselective cyclization, which formally constitutes remote 1,6 induction mediated PS-BEMP. This allowed construction complex with up to four stereocenters, excellent enantioselectivities (up 95% ee), complete control in...

The syntheses of the quinoxaline and pteridine proligands (3 4) related to molybdopterin are described 3 has been characterised complexed via its dithiolene group a CpCo(III) centre (5). Each 3–5 sensitive hemiaminal unit molybdopterin, unprotected, verifying stability in vitro.

The total synthesis of the sesquiterpenoid xylarenal A is reported. This first synthetic entry to an eremophilane terpenoid with exocyclic vinyl aldehyde unit involves use bicyclic enone (+)-3, which after a γ-oxidation and α'-allylation leads formation ketone (+)-8. After its acylation, oxidative cleavage allyl side chain followed by α-methylenation resulting gives (+)-xylarenal (1). (−)-xylarenal from (−)-3 also Moreover, trinoreremophilane (+)-1α-hydroxyisoondetianone (5) described.

Two approaches to tetrahydro-[1H]-2-benzazepin-4-ones of interest as potentially selective, muscarinic (M(3)) receptor antagonists have been developed. Base promoted addition 2-(tert-butoxycarbonylamino)methyl-1,3-dithiane with 2-(tert-butyldimethylsiloxymethyl)benzyl chloride gave the corresponding 2,2-dialkylated 1,3-dithiane which was taken through dithiane derivative parent 2,3,4,5-tetrahydro-[1H]-2-benzazepin-4-one by desilylation, oxidation and cyclisation via a reductive amination....

Abstract A general strategy for the synthesis of aignopsanes, a new family sesquiterpene natural products marine origin, is presented. The total (+)‐aignopsanoic acid ( 1 ), (−)‐methyl aignopsanoate 2 and (−)‐isoaignopsanoic 3 ) has been achieved their absolute configuration confirmed. (+)‐Microcionin‐1 4 structurally related furanosesquiterpene isolated in both enantiomeric forms from sponges, was also synthesized its established an unambiguous way. Interestingly, we report that...

Abstract An unprecedented C−C coupling reaction between alkenes and ketones by hydrogen‐atom transfer, using Fe(acac) 3 PhSiH in EtOH, is described. This mild protocol features high site selectivity allows the construction of sterically congested structures containing tertiary alcohols quaternary centers. The overall process introduces a novel strategic bond disconnection for ring‐closing reactions.

A revised structure for the Lycopodium alkaloid huperzine N is proposed and confirmed by synthesis. The key synthetic steps involve an epimerization of a cis-5-oxodecahydroquinoline to corresponding trans isomer coupling, followed diastereoselective hydrogenation using Wilkinson's catalyst incorporate pyridylmethyl moiety. This route allowed serralongamine be synthesized first time, two additional led N, both products bearing unusual decahydroquinoline stereostructure.