Hajime Hiramatsu

Enantioselective Cu-catalyzed 1,4-addition of Me3Al to a 4,4-disubstituted cyclohexa-2,5-dienone

Abstract A series of chiral enantiomerically pure 2-aryloxazolines was synthesized. (4 S )-2-(2′,6′-dimethoxyphenyl)-4-isopropyloxazoline proved to be an efficient chiral ligand for the Cu-catalyzed conjugate addition of Me 3 Al to cyclohexadienone, and by using 20mol% of this ligand, 1,4-adduct was obtained in 68% ee. In addition, TBDMSOTf is crucial for the asymmetric conjugate addition to proceed with good chemical yield and high ee.

Isolation and structure determination of TMC-151s: Novel polyketide antibiotics from Gliocladium catenulatum Gilman & Abbott TC 1280.

Abstract Six new antibiotics, TMC-151 A-F (2–7) have been isolated from organic extracts of the fermentation broth of Gliocladium catenulatum Gilman & Abbott TC 1280, isolated from a soil sample. Their structures including the absolute stereochemistries, were determined by extensive analyses of NMR and X-ray crystallography, and degradation studies. TMC-151s are novel polyketides containing D-mannopyranoside and D-mannitol or D-arabitol. These antibiotics showed moderate cytotoxicity to several tumor cell lines.

STRUCTURES OF TMC-120A, B AND C, NOVEL ISOQUINOLINE ALKALOIDS FROM ASPERGILLUS USTUS TC 1118

Abstract Three novel isoquinoline alkaloids, TMC-120A, B and C ( 1–3 ) have been isolated from a fermentation broth of Aspergillus ustus (Bain.) Thom & Church TC 1118, a fungus isolated from rhizosphere of grass. Their structures were determined through extensive spectroscopic analyses and chemical studies. TMC-120s ( 1–3 ) are found to be the first furo[3,2- h ]isoquinoline-type alkaloids isolated from natural sources.

Crystal structure–solubility relationships in optical resolution by diastereomeric salt formation of DL-phenylglycine with (1S)-(+)-camphor-10-sulfonic acid

The experimentally-optimized optical resolution of DL-phenylglycine (PG) with (1S)-(+)-camphor-10-sulfonic acid ((+)-CS) afforded the crystalline D-PG·(+)-CS salt in 45.7% isolated yield and 98.8% optical purity. This excellent resolution has been studied by comparison of the crystal properties of the diastereomeric salt pair, D- and L-PG·(+)-CS. Thermoanalysis (DSC) of the less-soluble D-PG·(+)-CS showed a higher melting point and a larger enthalpy of fusion than those of the more-soluble L-PG·(+)-CS. The difference in the solubilities of the two salts in water is very large because the more-soluble L-PG·(+)-CS is freely soluble. The X-ray crystal structure of D-PG·(+)-CS shows a dense and stable molecular conformation of alternating PG cation layers and (+)-CS anion layers, whereas that of L-PG·(+)-CS shows a coarser molecular conformation consisting of characteristic “holey” vacancy layers, an important factor in its free solubility. The difference in the two characteristic structures could be closely related to the high efficiency of the resolution. A geometrical discussion of the (+)-CS molecule predicted that its excellent resolving ability may be due to its combining two structural functions; a hydrophilic flexible methanesulfonic acid site and a hydrophobic rigid camphor site.

A highly stereoselective synthesis of 3-hydroxy-1-aryltetralin lignans based on the stereoselective hydroxylation of α,β-dibenzyl-γ-butyro-lactones: the first synthesis of (±)-cycloolivil

Lignans of the 3-hydroxy-1-aryltetralin series 1 and 2 have been synthesised in good yields in a highly diastereoselective manner. The stereochemistry at C-1, C-2 and C-3 of 1 and 2 was completely controlled by an electrophilic addition of oxodiperoxymolybdenum(pyridine)hexamethylphosphoric triamide (MoOPH) to the metal enolates of α,β-disubstituted γ-butyrolactones 4 and the Friedel–Crafts type intramolecular cyclisation of 3. This method was applied to the stereoselective synthesis of (±)-cycloolivil 1e.

Enantioselective catalytic Diels–Alder reaction of ethyl 2-benzoylacrylate with chiral bis(oxazoline)– or mono(oxazoline)–magnesium complex

The magnesium catalysed Diels–Alder reaction of 2-benzoylacrylate gave the endo-adduct enantioselectively with bis(oxazoline) 5 as a C 2 -symmetric ligand or mono(oxazoline) 4 as a non-C 2 -symmetric ligand.

Synthesis of bicyclo[4.1.0]hept-2-enes (trinorcarenes) by photochemical reaction of bicyclo[2.2.2]oct-5-en-2-ones

Photochemical reaction of bicyclo[2.2.2[oct-5-en-2-ones has been investigated as a prelude to focused application to the synthesis of sesquiterpenes such as sesquicarene and sirenin. Diels–Alder reaction of cyclohexa-2,4-dienes, having different substituents (methylthiomethyl and methoxy) at the C-6 position, with a dienophile proceeds regio- and stereo-selectively to give bicyclo[2.2.2]oct-5-en-2-ones; their photolysis in benzene upon high-pressure Hg lamp irradiation affords decarbonylation products, bicyclo[4.1.0]hept-2-enes (trinorcarenes), stereoselectively. Replacement of the methylthiomethyl group with a 2-ethoxycarbonylvinyl group improves the sequential reaction.