Okiko Miyata

β- and α-lithiaton of methyl β-methoxyacrylate: efficient synthesis of α,γ-substituted methyl tetronates - structure of aspertetronins and gregatins

Abstract Methyl β-methoxyacrylate ( 1 ) can be lithiated successively in β- and α-positions. Reaction with two electrophiles (at first a carbonyl compound) leads to α, γ-substituted methyl tetronates in a two step synthesis. Application of this method to the synthesis of methyl tetronate whose structure was assigned as that of gregatin B indicates that the gregatins and aspertetronins have the isomeric structures 17 .

Novel intermolecular carbon radical addition to a nitrone: asymmetric synthesis of α-amino acidsElectronic supplementary information (ESI) available: experimental procedures. See http://www.rsc.org/suppdata/cc/b2/b211570k/

A nitrone was used as a synthetically useful radical acceptor in carbon–carbon bond-forming radical reactions; the intermolecular addition of alkyl radicals to chiral glyoxylic nitrone was studied; a high degree of stereocontrol in radical addition to glyoxylic nitrone was achieved to provide a new method for asymmetric synthesis of α-amino acids.

EFFICIENT SYNTHESIS OF INDOLES AND BENZO[b]FURANS VIA [3,3]-SIGMATROPIC REARRANGEMENT OF N-TRIFLUOROACETYL ENEHYDRAZINES AND ENEHYDROXYLAMINES

- This review summarizes an efficient synthesis of benzo[b]furans and indoles via [3,3]-sigmatropic rearrangements of N-trifluoroacetyl enehydroxylamines and enehydrazines, which were triggered by acylation of oxime ethers and hydrazines. TFAA and TFAT-DMAP have been proved to be the best reagent to induce [3,3]-sigmatropic rearrangement for the synthesis of benzo[b]furans and indoles. This method was successfully applied to the short synthesis of natural products.

Asymmetric induction at two contiguous stereogenic centers by diastereoface differentiating nucleophilic addition reaction

Abstract Distereoface differentiating nucleophilic of thiophenol to olefins delivers a new concomitant asymmetric construction of two contiguous stereogenic centers and has been successfully applied to the asymmetric synthesis of (+)-diltiazem.

Copper-catalyzed synthesis of trisubstituted isoxazoles via a cascade cyclization-migration process.

An atom-economical, catalytic, and regioselective synthesis of 3,4,5-trisubstituted isoxazoles has been successfully developed. Treatment of O-arylmethyl alkynyl oxime ethers with 5 mol % of Cu(OTf)(2) in chlorobenzene at reflux gave 4-arylmethylisoxazoles in good to excellent yields via the sequential intramolecular addition of the oxime moiety to the alkyne with subsequent 1,3-migration of the arylmethyl group.

Synthesais of Corynanthe Alkaloids Corynantheine, Hirsuteine, and the Isositsirkines

Total syntheses of corynanthe alkaloids including eight possible stereisomers of isositsirikines along with corynantheine and hirsuteine according to two different approaches are described, thereby unambiguously solved the pending problems on the stereochemistry of these alkaloids.

Aerobic hydroxylation of N-borylenamine: triethylborane-mediated hydroxyalkylation of alpha,beta-unsaturated oxime ether.

Intermolecular hydroxyalkylation of alpha,beta-unsaturated imines involving Et3B-mediated regioselective alkyl radical addition and subsequent hydroxylation with molecular oxygen has been developed, in which N-borylenamine generated by trapping of the enaminyl radical with Et3B was a key intermediate in the proposed aerobic hydroxylation mechanism.

Radical cyclisation in heterocycle synthesis. Part 1. Sulfanyl radical addition–cyclisation of dienylamides for lactam synthesis

A new method for the synthesis of five- to eight-membered lactams by sulfanyl radical mediated addition–cyclisation of dienylamides is described. The sulfanyl radical addition–cyclisation of the dienylamide 1 was systematically investigated under four different conditions and was found to give the cyclised lactams 2–6 in 54–79% yield. The stereo- and regio-selectivity of sulfanyl radical addition–cyclisation was established from the preferential formation of the trans-cyclised lactam 3 and also from the substituent effects in the Cyclisation of the dienylamides 11–18. The sulfanyl radical mediated addition–cyclisation was successfully applied to the construction of the six- and eight-membered lactams 28a, b.

Synthesis of Dihydrobenzofurans with Quaternary Carbon Center under Mild and Neutral Conditions

A new method has been developed for the construction of dihydrobenzofurans from O-aryloxime ethers bearing an α-cyano group using a sequential regioselective isomerization/[3,3]-sigmatropic rearrangement/cyclization reaction in MeOH without any catalysts under neutral conditions at ambient temperature. The current transformation provides environmentally benign and atom-economical access to a variety of dihydrobenzofurans containing a quaternary carbon from readily available cyclic and acyclic oxime ethers.

Reaction of polychloroacetamides with amines : Reductive dechlorination and aziridine formation

Treatment of trichloroacetamides with amines undergoes reductive dechlorination via single-electron transfer process to afford dichloroacetamides in good yields. Reaction of trichloro- and dichloroacetamides with DBU provides a new synthetic method of aziridinopyrrolidines.