Synthesis of cyclopropa[c]indeno[1,2-b]quinolines through a MCR/Staudinger/aza-Wittig sequence

Spirocyclopropanes were prepared from aromatic aldehydes, 1,3-indandione and acetophenones through a halogenation/S_N2-displacement/Michael-initiated ring-closing sequence by a pyridinium-ylide-assisted multicomponent reaction, and their further use was also researched in the construction of cyclopropa[c]indeno[1,2-b]quinolines through subsequent Staudinger/aza-Wittig reactions.     

New spiro-fused 2-nitrocyclopropanecarboxylates: Synthesis and structure

Reactions of alkyl 3-bromo-3-nitroacrylates with cyclic CH-acids, Meldrum’s acid or 3-methyl-1-phenylpyrazol-5-one, afford new spiro-fused 2-nitrocyclopropanecarboxylates. In the case of Meldrum’s acid, the products are formed as individual diastereomers. The obtained experimental results are confirmed by quantum chemical calculations (B3LYP/6-311+G(d,p) taking into account solvent effects).