A new convenient four-component synthesis of 6-amino-2H, 4H-pyrano[2,3-c]pyrazole-5-carbonitriles and one-pot synthesis of 6 ′-amino-5-cyano-1,2-dihydrospiro-[(3H)-indole-3,4 ′-(4 ′H)-pyrano[2,3-c]pyrazol]-2-ones