3-OKSOPROPANNİTRİLLERİN MANGAN(III) ASETAT ARACILIĞINDA ?,ß-DOYMAMIŞ AMİTLERLE RADİKALİK HALKALAŞMA REAKSİYONLARI VE 4-SİYANO-2,3-DİHİDROFURAN-3-KARBOKSİAMİTLERİN SENTEZİ (Free Radical Cyclization of 3-oxopropanenitriles Mediated Manganese(III) Acetate with ?,ß-Unsaturated Amides and Synthesis of 4-cyano-2,3-dihydrofuran-3-carboxyamides)