Yasuhiro Nishitani

Synthesis of amphotericin B. 2. fragment C-D of the aglycone

Abstract Fragment C-D, the C(21)-C(37) unit of the aglycone of amphotericin B, has been synthesized.

Synthetic studies on β-lactam antibiotics. VII. Mild removal of the benzyl ester protecting group with aluminum trichloride☆

The benzyl ester protecting group in β-lactam derivatives can be cleanly removed by treatment with aluminum trichloride under mild conditions, preferably in the presence of anisole, to give the corresponding free acids in high yields.

Stereocontrolled, straightforward synthesis of 3-substituted methyl 7α-methoxy-1-oxacephems☆

Abstract Stereocontrolled and industrially feasible synthesis of a new antibiotic 1a and related derivatives, which is characterized by using all the carbon atoms of the penicillin skeleton, is described.

Novel semi-synthetic glycopeptide antibiotics active against methicillin-resistant staphylococcus aureus (MRSA) and vancomycin-resistant Enterococci (VRE): doubly-modified water-soluble derivatives of chloroorienticin B

A series of N-alkylated and aminomethylated derivatives of chloroorienticin B, a vancomycin-related glycopeptide antibiotic, were synthesized. Doubly-modified derivatives having both hydrophobic and hydrophilic substituents exhibited potent antibacterial activity against MRSA and VRE along with considerable water-solubility.

Synthetic studies on β-lactam antibiotics. 13. Transformation of 6-epipenicillins to 2R-{(1S, 5R)-2-oxa-6-oxo-4,7- diazabicyclo[3.2.0]hept-3-en-7-yl}-3-methylbut-3-enoates

Abstract Reaction of 2β-unsubstituted or functionalized-methyl 6-epipenicillin sulfoxides 2 with tervalent phosphorus compounds gave azetidinone-epi-oxazolines 3 , important intermediates in synthesis of 7α-methoxy-1-oxacephems. Preparation of the 2β-functionalized-methyl substrates is described also.

An efficient and practical method for solid-phase synthesis of tripeptide-bearing glycopeptide antibiotics: combinatorial parallel synthesis of carboxamide derivatives of chloroorienticin B.

An efficient and practical method was established for solid-phase parallel synthesis of the peptide-bearing carboxamide derivatives of chloroorienticin B, and over 80 compounds were synthesized simultaneously. Among the derivatives prepared, compounds having both tryptophan and tyrosine residues (1-3) were found to possess potent antibacterial activity against VRE.

A new method for regioselective synthesis of a broad-spectrum parenteral S-3578-related cephalosporin bearing an imidazo[4,5-b]pyridinium derivative at C-3'

A broad-spectrum S-3578-related cephalosporin, 7β-[2-(5-amino-1,2,4-thiadiazol-3-yl)-2(Z)-fluoromethoxyiminoacetamido]-3-[1-(3-methylaminopropyl)-1H-imidazo[4,5-b]pyridinium-4-yl]methyl-3-cephem-4-carboxylate sulfate was regioselectively synthesized in a good yield using diaminopyridine derivative bearing a dimethylformamidine group.

Synthetic studies on β-lactam antibiotics. part 11. Completely stereocontrolled synthesis of 7α-unsubstituted 1-oxacephems from penicillins

Abstract A cis intermediate 3 was obtained by novel reductive cleavage of 2 , prepared from 1 in 6 steps including a new ester to ketone conversion. Regioselective bromination of 3 followed by substitution and known conversions gave 1-oxacephems 5 .