The first naturally occurring aromatic isothiocyanates, rapalexins A and B, are cruciferous phytoalexins

The discovery of the first naturally occurring aromatic isothiocyanates, indole-3-isothiocyanates, their first synthesis, antimicrobial activity and proposed biogenetic origin in canola plants are reported.     

Tandem Claisen rearrangement and ruthenium catalyzed enyne bond reorganization as a route to the synthesis of tricyclic 1,8-naphthyridinones

A novel procedure for the synthesis of substituted 1,8-naphthyridinones via tandem Claisen rearrangement and ring-closing enyne metathesis is reported.     

A flexible route to (5R)-thiolactomycin,a naturally occurring inhibitor of fatty acid synthesis

[formula: see text] A new and efficient asymmetric synthesis of naturally occurring (5R)-thiolactomycin (1) using D-alanine as the source of chirality is described.     

A room temperature alternative of the Claisen rearrangement route to ortho allylated phenols: unique reactivity pattern of allylindium reagents

Quinol ethers and quinone monoketals are shown to undergo formal anti-Michael addition reactions with allylindium reagents at room temperature to give only ortho allylated phenols in good yields.     

The dioxanone-to-dihydropyran Claisen rearrangement. Synthesis of C(7)-C(13) fragments of erythronolides A and B

Iterative applications of the dioxanone-to-dihydropyran Claisen rearrangement have resulted in the efficient conversion of (S)-(−)-ethyl lactate to the erythronolide A and B C(7)C(13) subunits 19, 23, and 27 via the common synthetic intermediates 13 and 22.     

A synergistic approach to polycyclics via a strategic utilization of Claisen rearrangement and olefin metathesis

Olefin metathesis promoted by a well-defined metal carbene complex has evolved into an efficient method for the construction of a broad range of carbocyclic and heterocyclic rings of varying size. The synthetic potential of the olefin metathesis has been further increased by combining various other C-C bond forming processes either in tandem or in sequence. Herein, application of Claisen rearrangement and olefin metathesis to prepare various intricate and/or biologically important targets has been described.     

Photocatalytic aerobic oxidation/semipinacol rearrangement sequence: a concise route to the core of pseudoindoxyl alkaloids

A visible light-induced photocatalytic aerobic oxidation/semipinacol rearrangement has been successfully developed. This methodology allows for efficient conversion of a wide range of indoles into the synthetically significant 2,2-disubstituted indolin-3-ones, the core structure of pseudoindoxyl alkaloids, under mild reaction conditions.     

Microwave-mediated reactions of 3-aminomethylpyridines with acetylenedicarboxylates. A novel synthetic route to dihydronaphthyridines and naphthyridine-1-ones

Reaction of 3-(1-alkylamino)pyridines with electron deficient acetylenes in the presence of acids yields 1,2-dihydro[2,7]naphthyridine-3,4-dialkyldicarboxylates 4 in 35-72% yield. Compounds 4 unsubstituted in position 1 can be easily oxidized with potassium permanganate into the respective naphthyridine-1-ones derivatives 5 in good yields.     

Synthesis of β,γ-disubstituted-γ-lactones through a Johnson–Claisen rearrangement: a short route to xylobovide,nor-canadensolide,canadensolide, sporothriolide and santolinolide

The Johnson–Claisen rearrangement of allyl alcohols with chiral vicinal diol functionality was employed to access chiral β,γ-disubstituted-γ-lactones in high enantio- and diastereoselectivity. These were efficiently converted into nor-canadensolide, the advanced γ-(lactone–lactol) intermediate for xylobovide, canadensolide and sporothriolide and the lactone moiety of the santolinolides.     

Total synthesis of psammaplysenes A and B, naturally occurring inhibitors of FOXO1a nuclear export

[reaction: see text] Two inhibitors of FOXO1a-mediated nuclear export, psammaplysenes A and B, have been synthesized by a flexible and efficient route. A common starting material, 4-iodophenol, was used to prepare both halves of these pseudosymmetric dibromotyrosine-derived metabolites.     

A direct route to isoflavan quinones. The synthesis of colutequinones A and B

The first syntheses of colutequinone A and colutequinone B were achieved. Radical generation via phenyliodoso diacetate was superior to radical generation via ammonium persulfate.     

A simple route to the syntheses of both enantiomers of trans-oak lactone and (+)-cis-oak lactone

Stereocontrolled syntheses of both enantiomers of trans-oak lactone and (+)-cis-oak lactone have been achieved from a common precursor.     

Photoinduced Molecular Transformations. Part 142. One-step syntheses of 1H-benz[f]indole-4,9-diones and 1H-indole-4,7-diones by a new regioselective photoaddition of 2-amino-1,4-naphthoquinones and 2-amino-1,4-benzoquinones with alkenes

The 2,3-dihydro-1H-benz[f]indole-4,9-diones 3a–d , h were formed in a one-step reaction in 13–82% yield by an unprecedented [3 + 2] regioselective photoaddition of 2-amino-1,4-naphthoquinone ( 1 ) with various electronrich alkenes 2 (Scheme 1, Table). The [3 + 2] photoadducts derived from 1 with vinyl ethers and vinyl acetate gave 1H-benz[f]indole-4,9-diones 4e , f , i , in 33–72% yield, by spontaneous loss of the corresponding alcohol or AcOH from the resulting adducts; 4i has a kinamycin skeleton. The [3 + 2] photoaddition also took place on irradiation of the differently substituted amino-1,4-benzoquinones 6 , 7 , and 12 and excess alkenes 2 in benzene, giving 1H-indole-4,7-dione derivatives 13 and 14 (Scheme 3), 15a and 16 (Scheme 4), and 18 (Scheme 4), respectively. The initial products in these photoadditions were proved to be hydroquinones, the air oxidation of which yielded the heterocyclic quinones; 2,3-dihydro-2-methoxy-2-methyl-5-phenyl-1H-indole-1,4,7-triyl triacetate ( 19 ) was isolated after treatment of the crude photoaddition mixture obtained from 2-amino-5-phenyl-1,4-benzoquinone ( 7 ) and 2-methoxyprop-1-ene ( 2f ) with Ac₂O and pyridine under N₂. A pathway leading to the annelated hydroquinones involving ionic intermediates arising from an electron transfer in these photoadditions is proposed (Scheme 5).     

A direct entry to the 1-methoxyindole skeleton and to the corresponding indoles by a novel rearrangement: general syntheses of substituted 1-methoxyindoles

A short and efficient route to 1-methoxyindoles via a novel rearrangement is disclosed. This route involves only three steps from commercially available nitro compounds. The methodology is also generalized with a variety of examples to afford a series of 2-substituted-1-methoxyindoles possessing an electron-withdrawing group at position 3. In addition, a 1-methoxyindole compound 10 was converted to the corresponding indole 11 under mild conditions thereby constituting a new synthesis of substituted indoles.     

A general route to 5,6-seco-hexahydrodibenzopyrans and analogues: first total synthesis of (+)-Machaeridiol B and (+)-Machaeriol B

A general and efficient route for the synthesis of 5,6-seco-hexahydrodibenzopyran and trans-hexahydrodibenzopyran analogues was established, via a highly regio- and stereoselective S_N2′ reaction of arylcyanocuprates to enol silyl ether of α,β-epoxycyclohexanone. It was applied to the first facile total synthesis of (+)-Machaeridiol B and (+)-Machaeriol B.     

The role of cesium fluoride in aryl propargyl ether Claisen rearrangement and its mechanistic elucidation: a theoretical study

The role of cesium fluoride (CsF) in aryl propargyl ether Claisen rearrangement and its mechanistic pathway have been investigated in gas and solvent phase using the density functional theory implemented in Gaussian 09. Our results indicate that the [3,3]-sigmatropic rearrangement is the rate-limiting step with ΔG ^? value of 37.1 kcal/mol in solvent phase. Furthermore, the results show that the enolization of α-allenylketone intermediate (Int1-CsF) has a higher free energy barrier, which implies that the formation of benzopyran is not favored in the presence of CsF. However, the abstraction of the α-hydrogen atom in Int1-CsF with CsF shows a very low free energy barrier and is the most favored pathway for aryl propargyl ether Claisen rearrangement in the presence of CsF to form benzofuran. In the case of substituted aryl propargyl ethers, a methoxy group on the benzene ring lowers the activation barrier. The HOMO–LUMO, conformational and NBO analysis indicate that increasing methyl substitution on the propargyl residue enhances the rearrangement reaction.     

A new route to 1-phenylnaphthalenes by cycloaddition: a simple and selective synthesis of some naphthalene lignan lactones

2-(2-Dithianyl)benzhydrols ($\text{2}$ a-c) undergo facile cycloaddition reaction with maleic anhydride under thermal conditions to give 1-phenyl-naphthalenes ($\text{7}$ a-c) in one step. The naphthalenes ($\text{7}$ a-c) have been converted into the naphthalene lignan lactones, ($\text{9}$ a-c) and ($\text{10}$ a-c).     

Highly diastereoselective and enantioselective C-H functionalization of 1,2-dihydronaphthalenes: a combined C-H activation/Cope rearrangement followed by a retro-Cope rearrangement

The Rh2(S-DOSP)4-catalyzed reaction of vinyldiazoacetates with dihydronaphthalenes results in a highly enantioselective (91-99.6% ee) and diastereoselective (>98% de) C-H functionalization. The apparent intermolecular C-H insertion was demonstrated to be a combined C-H activation/Cope rearrangement followed by a retro-Cope rearrangement.