ChemInform Abstract: REACTIONS OF BENZYL 6-Isocyanopenicillanate WITH THIOCARBONYL REAGENTS. NOVEL REARRANGEMENTS OF 2,3-Dihydrothiazolo(2,3-B)(1,3)thiazin-5-Ones VIA PENAM CARBON-5-CARBON-6 BOND CLEAVAGE. X-Ray CRYSTAL STRUCTURE AND ABSOLUTE CONFIGURATIO