Stereoselective reactions. IX. Synthetic studies on optically active .BETA.-lactams. I. Chiral synthesis of carbapenam and carbapenem ring systems starting from (S)-aspartic acid.
作者:NOBUO IKOTA、HISANARI SHIBATA、KENJI KOGA
DOI:10.1248/cpb.33.3299
日期:——
A chiral carbapenam ring system ((3R, 5R)-(+)-19 and -20) having the desired absolute configuration at C-5 was synthesized starting from (S)-aspartic acid, and the latter product was further transformed to a chiral carbapenem derivative ((5S, 2'R)-(+)-21) having an (R)-cysteine moiety as a side chain.
Conjugate addition-rearrangement of N-substituted hydroxylamines to α,β-unsaturated D-lactones provides a short and effective route to 3-substituted isoxazolidin-5-ones. These compounds were converted into 4-substituted azetidin-2-ones via a two-step procedure involving hydrogenolysis of the NO bond followed by cyclization of the resulting β-amino acids. N-Benzyl-4-(3′-acetoxy-2′-tert-butyldimeth
As a key intermediate for the synthesis of monobactam analogues, cis-3-benzyloxycarbonyl-amino-4-(2-hydroxyehtyl)-2-azetidinone was synthesized from (4S)-4-methoxycarbonylmethyl-2-azetidinone, and converted into monobactams having a methoxyethyl group at the C-4 position of the β-lactam ring. Among the compounds synthesized, disodium (3S, 4R)-3[2-(2-aminothiazol-4-yl)-(Z)-2-carboxymethoxyiminoacetamido]-4-(2-methoxyethyl)-2-azetidinone-1-sulfonate showed strong activity against a variety of gram-negative bacteria except Pseudomonas aeruginosa. Furthemore, the 4-methoxyethyl derivatives exhibited excellent stabiliy to β-lactamases, and the syntheses of the corresponding trans isomer and 3α-methoxy derivatives are also described.
A stereoselective synthesis of the known synthetic intermediate (13) for (-)-carpetimycin a (1) has been achieved starting from the monocyclic β-lactcon (8b) by the novel use of the direct aldolcondensation of 8b with acetone via the titaniun enolate.
Enantioselective synthesis of (1R,4R)-2-azabicyclo[2.2.0]-hexane-3,5-dione and (1R, 4R,5S)-5-hydroxy-2-azabicyclo[2.2.0] hexan-3-one (newbuildingblocks for carbapenems) from 4-(ℓ-menthoxy)-pyridin-2(1H)-one via photopyridone formation is reported.