A comparative study of the preparations of p-nitrophenyl and n-hydroxysuccinimido tert-butyloxycarbonyl amino acid esters, and synthesis of carboxamide protected isoasparagine and glutamine derivatives
Abstract
This investigation was aimed at the synthesis of
two new potential protecting groups for the carboxamide
side chain of the asparagine and glutamine. A
comparative study of preparations of p-nitrophenyl and
N-hydroxysuccinimido tert-Butyloxycarbonyl amino acid
esters was carried out.
The synthesis of 4-methoxy~-methylbenzylamine
and 3-methylbenzhydrylamine precursors for the carboxamide
protecting groups was attempted. The 4-methoxy-
2-methylaniline was diazotized and Sandmeyer reaction
was utilized to obtain 4-methoxy-Z-methylbenzonitrile.
This nitrile was reduced with lithium aluminium hydride
to give 4-methoxy-Z-methylbenzylamine. The synthesis
of m-bromotoluen was carried out by acetylating ptoluidine,
followed by bromination and the removal of ,:
the acetyl group by hydrolysis, diazotization, and
replacement o£-NZ with hydrogen. Grignard reagent,
3-methylphenyl magnesium bromide, was prepared in
anhydrous ether solution from. magnesium turnings and
the m-bromotoluene. The 3-mehylpnenyl magnesium
bromide was coupled with benzonitrile followed by acid
hydrolysis to give 3-methylbenzophenone. The synthesis
of 3-methylbenzhydrylamine from the 3-methylbenzophenone
by the Leuckart reaction was unsuccessful