The synthesis of new 6-exomethylene penams with benzothiazole ring was described. The 6,6-dibromopenam 5 was treated with $CH_3$MgBr and carbaldehyde 4 to afford the 6-bromo-6-(1-hydroxy-1-methyl)penicillanate 6, which was reacted with acetic anhydride to give acetoxy compound 7. The deacetobromination of acetoxy compound 7 with zinc and acetic acid gave 6-exomethylene penams, Z-isomer 8 and E-isomer 9, which was oxidized to sulfones 10 by m-CPBA. The p-methoxybenzyl compounds 6~10 were deprotected by AlCl$_3$ and neutralized to give the sodium salts 11~15.