| abstract |
A compound of the formula :n vherein R 11 is (C 1 -C 6 )alkanoyl or a group of the formula :n R 5 is amino or protected amino, and R 6 is hydrogen or an organic group which may have suitable substituent(s), R 3 is carboxy or protected carboxy, and Y 2 is (C 1 -C 6 )alkanesulfonyloxy, and a salt thereof and processes for the preparation thereof. |