Question

Which among the following Cephalosporins has an unusual 5-thio-1,2,3,4-tetrazole substituent attached to core heterocyclic nucleus through a methylene bridge?

• A. Cefazolin
• B. Cefamandole
• C. Cefoxitin
• D. Cefadroxil

Answer 1

The Correct Option is B

To determine which cephalosporin has an unusual 5-thio-1,2,3,4-tetrazole substituent attached to the core heterocyclic nucleus via a methylene bridge, let's examine the specific structures of the given options.

1. Cefazolin: This cephalosporin has a thio-linked thiazolidine ring but lacks the 5-thio-1,2,3,4-tetrazole group.
2. Cefamandole: This cephalosporin is known to have a 5-thio-1,2,3,4-tetrazole substituent. This distinctive feature is key to identifying Cefamandole's unique chemical structure.
3. Cefoxitin: This belongs to the cephamycin subgroup, possessing a methoxy group at the 7α-position, but it does not have the specific 5-thio-1,2,3,4-tetrazole substituent.
4. Cefadroxil: This is a first-generation cephalosporin which does not include a 5-thio-1,2,3,4-tetrazole group in its structure.

Thus, Cefamandole is the correct answer as it is the only cephalosporin among the options that has the unusual 5-thio-1,2,3,4-tetrazole substituent linked through a methylene bridge to its core nucleus.

Conclusion: The cephalosporin with the unusual 5-thio-1,2,3,4-tetrazole substituent is Cefamandole.