Synthesis of optically active imidazolines, azapenams, dioxocyclams, and bis-dioxocyclams

Optically active 4-methyl-4-carbomethoxy-Delta(2)-imidazoline was efficiently synthesized on a multigram scale. Photolysis with (methoxymethylcarbene)chromium complex produced the optically active azapenam in good yield and with high stereoselectivity. Acid-catalyzed dimerization followed by reduction produced the corresponding optically active dioxocyclam in good yield. Using a bis-carbene complex, an optically active bis-dioxocyclam was produced in excellent yield.