Synthetic studies on β-lactam antibiotics. Part 10. Synthesis of 7β-2-carboxy-2-(4-hydroxyphenyl)acetamido-7.alpha.-methoxy-3-[(1-methyl-1H-tetrazol-5-yl)thiomethyl]-1-oxa-1-dethia-3-cephem-4-carboxylic acid disodium salt (6059-S) and its related 1-oxacephems | Synapse