Osamu Morikawa

One-pot synthesis of naphtho[2,3-b]furan-4,9-diones by sequential coupling/ring closure reactions

Abstract Treatment of 3-phenyliodonio-1,2,4-trioxo-1,2,3,4-tetrahydronaphthalenides with terminal acetylenes in the presence of a bis(triphenylphosphine)palladium chloride-cuprous iodide catalyst or cuprous oxide in N -methylpiperidine or pyridine, respectively, furnished the corresponding 2-substituted naphtho[2,3- b ]furan-4,9-diones in moderate to good yields. The utility of this method was demonstrated in the synthesis of a cytotoxic natural product, 2-(1-hydroxyethyl)naphtho[2,3- b ]furan-4,9-dione.

Synthesis of 3-methoxyquinolines via cyclization of 1-isocyano-2-(2-lithio-2-methoxyethenyl)benzenes

Abstract 2-(2-Isocyanophenyl)acetaldehyde dimethyl acetals were treated with excess LDA to generate 1-isocyano-2-(2-lithio-2-methoxyethenyl)benzenes, which cyclized intramolecularly to afford 3-methoxyquinolines in good to excellent yields.

The acid-catalyzed condensation of 2-propylresorcinol with formaldehyde diethyl acetal. The formation and isomerization of calix[4]resorcinarene, calix[5]resorcinarene, and calix[6]resorcinarene

Abstract The title reaction initially produced a mixture of three cyclic oligomers, calix[n]resorcinarenes (n= 4, 5, 6), as the major products. Under the conditions of their formation, the pentamer rapidly isomerized to the tetramer and the hexamer, while the hexamer slowly isomerized to the tetramer. A new cyclic oligomer, calix[5]resorcinarene, was isolated and characterized.

Convenient synthesis of furopyranopyrandione derivatives by the can-mediated furan ring formation

4H,9H-Furo[3,2-c]pyrano[3,4-e]pyran-4,9-dione (8) and (10) and 4H,5H-furo[2,3-b]pyrano[3,4-e]pyran-4,5-dione derivatives (9) were prepared in one step by treating 4-hydroxy-2H,5H-pyrano[4,3-b]pyran-2,5-diones (6) and alkenes (7) (or phenylacetylene) in acetonitrile with 2 equivalents of cerium(IV) ammonium nitrate (CAN).

Crystal Structure of C-(n-propyl)calix[4]resorcinarene and its Complex with Caffeine

Abstract The crystal structures of the all-cis epimer of C-(n-propyl)calix[4]resorcinarene (1) and its caffeine complex are reported. 1 · CH3CN · H2O (2) crystallizes in the tetragonal space group P4, a = 14.3645(9), c = 9.3344(8) Å, V = 1926(2) Å3. Refinement led to a final conventional R 1 value of 0.047 for 3406 reflections and 236 parameters. The caffeine complex 1 · C8H10N4O2 · CH3OH · H2O (3) crystallizes in the triclinic space group P1, a = 11.2892(4), b = 13.0367(8), c = 16.9700(11) Å, α = 82.902(2), β = 79.713(3), γ = 88.053(2)°, V = 2438(2) Å3. Refinement led to a final conventional R 1 value of 0.067 for 6393 reflections and 641 parameters. The resorcinarene displays the usual bowl shape in both compounds. The caffeine molecule in 3 is hydrogen bonded to two resorcinarene and one water molecules and one of its methyl groups is included in the cavity of a third macrocycle, suggesting CH3…π interactions. Extended hydrogen bonding patterns involving phenolic protons and solvent molecules are also present in both compounds.

A facile synthesis of 1,1-disubstituted isoindoline derivatives by intramolecular iodoamination of 2-vinylbenzylamine derivatives

The intramolecular iodoamination of N-(2-vinylbenzyl)acetamide derivatives, derived from α-substituted 2-vinylbenzonitriles in two steps, afforded the corresponding 2-acetyl-1 -iodomethylisoindoline derivatives, which were transformed into the 1-methyl or 1-sulfenylmethyl derivatives by tributyltin hydride reduction or substitution by sodium thiolates, respectively, in reasonable yields.

One-pot synthesis of isoquinoline-5,8-dione derivatives from acylquinones and enamines

Abstract A new and facile method for the preparation of isoquinolinequinone derivatives has been developed. Treatment of 2-acyl-1,4-naphthoquinones or 2-acyl-5,6-dimethyl-1,4-benzoquinones with enamines (or imines), followed by addition of aqueous NH 3 in MeOH afforded benz[ g ]isoquinoline-5,10-dione or isoquinoline-5,8-dione derivatives, respectively, in moderate to good yields.

Convenient synthesis of 1,2-dihydroquinoline-3-carboxylic acid and 2H-1-benzothiopyran-3-carboxylic acid derivatives

A new and efficient method for the preparation of 1,2-dihydroquinoline-3-carboxylic acid derivatives via a magnesium amide-induced sequential conjugate addition–aldol type condensation reaction between 2-(alkylamino)phenyl ketones and α,β-unsaturated carboxylic acid derivatives, followed by simple dehydration, is described. The method can be applied to the synthesis of 2H-1-benzothiopyran-3-carboxylic acid derivatives using 2-mercaptobenzophenone in place of 2-(alkylamino)phenyl ketones.

α-Sulfenylalkylation of carbonyl compounds at the α-position via magnesium amide-induced enamine sulfenylalkylation with sulfoxides

Abstract The reactions of enamines with sulfoxides bearing α-hydrogens in the presence of a magnesium amide, generated in situ from the reaction of ethylmagnesium bromide with diisopropylamine, afforded the corresponding α-sulfenylalkylated ketones and aldehydes in isolated yields ranging from 39 to 76%. This procedure was successfully extended to the bis(methylthio)methylation with methyl (methylthio)methyl sulfoxide.

Functionalization at the extraannular positions of calix[4]resorcinarene using a Mannich-type thiomethylation

Abstract Treatment of calix[4]resorcinarene 1 with thiols and formaldehyde in the presence of triethylamine gave thiomethylated calix[4]resorcinarenes 2 in moderate yields. The thiomethylation also took place in acetic acid.