1: Methyltriphenylphosphonium bromide With potassium tert-butylate in tetrahydrofuran T=20°C; 1.5 h; 2: ethyl 6-oxo-1a,6-dihydro-1H-cyclopropa[a]indene-6a-carboxylate in tetrahydrofuran T=0 - 20°C;