Premium
On the Preparation of 2‐Substituted Cephalosporins, Part 2
Author(s) -
Tamás László,
Gunda Tamás E.,
Batta Gyula,
Sztaricskai Ferenc
Publication year - 2003
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.200390018
Subject(s) - chemistry , diazomethane , cycloaddition , moiety , cephalosporin , cephem , enol , substituent , enone , medicinal chemistry , ethyl diazoacetate , keto–enol tautomerism , organic chemistry , stereochemistry , cyclopropanation , catalysis , tautomer , carboxylic acid , biochemistry , antibiotics
Cephalosporin sulfoxides 1 and 2 containing an enone‐ or dienone‐type moiety at position 2 were treated with 2,3‐dimethylbuta‐1,3‐diene or diethyl azodicarboxylate to synthesize, in DielsAlder reactions, the new cephalosporin derivatives 4 and 5 with a cyclic substituent ( Scheme 1 ). Under the same conditions, ethyl diazoacetate and diazomethane reacted differently: while reactions of 1 and 3 with the former lead to compounds 7 – 10 corresponding to the 1,3‐dipolar cycloaddition route ( Scheme 2 ), diazomethane produced only enol ethers 12 and 13 , respectively ( Scheme 3 ). This difference could be rationalized by assuming two different reaction pathways: an orbital‐symmetry‐controlled concerted cycloaddition and an ionic one.
Accelerating Research
Robert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom
Address
John Eccles HouseRobert Robinson Avenue,
Oxford Science Park, Oxford
OX4 4GP, United Kingdom