Divergent Transformations of 2-Nitro-1 H-benzo[ f]chromenes in Reactions with Alkylidenemalononitriles: Access to Naphtho[2,1- b]furans via Base-Mediated Pyran Ring Contraction

Kirill S Korzhenko; Anastasiya S Yushkova; Dmitry V Osipov; Daria A Rashchepkina; Oleg P Demidov; Vitaly A Osyanin

doi:10.1021/acs.orglett.3c03879

Divergent Transformations of 2-Nitro-1 H-benzo[ f]chromenes in Reactions with Alkylidenemalononitriles: Access to Naphtho[2,1- b]furans via Base-Mediated Pyran Ring Contraction

Org Lett. 2024 Feb 23;26(7):1310-1315. doi: 10.1021/acs.orglett.3c03879. Epub 2024 Feb 8.

Authors

Kirill S Korzhenko¹, Anastasiya S Yushkova¹, Dmitry V Osipov¹, Daria A Rashchepkina¹, Oleg P Demidov², Vitaly A Osyanin¹

Affiliations

¹ Samara State Technical University, 244 Molodogvardeyskaya St., Samara 443100, Russia.
² North Caucasian Federal University, 1 Pushkina St., Stavropol 355009, Russia.

PMID: 38329453
DOI: 10.1021/acs.orglett.3c03879

Abstract

The action of 2-(1-arylethylidene)malononitriles on 2-nitro-1H-benzo[f]chromenes in the presence of Et₃N and MoO₃·2H₂O results in naphtho[2,1-b]furans containing an allylidenemalononitrile unit in the α-position. The reaction proceeds with contraction of the pyran ring via a cascade carba-Michael addition/retro-oxa-Michael reaction/tautomerization/S_N2/oxidation process. In contrast, the reaction of 2-nitro-1H-benzo[f]chromenes with the cyclic Knoevenagel adduct derived from 1-indanone and malononitrile leads to dihydroindeno[1,2-c]xanthenes. The possibility of further transformations of naphtho[2,1-b]furan derivatives as useful precursors and their optical properties were also investigated.