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The reactions of (−)‐cis‐verbenol epoxide with a number of aromatic aldehydes containing OH and/or MeO groups in the presence of montmorillonite K10 clay have been studied. Several new O‐containing heterocyclic compounds with different frameworks, including compounds with a previously unknown octahydro‐2H‐4,6‐(epoxymethano)chromene framework, have been synthesized. Introduction of one donor substituent in the benzaldehyde molecule led to a decrease in the total yield of intermolecular by formed products, while the introduction of two and more substituents led to an increase in the yield of these products.

SummaryConditions enabling the single-step preparative synthesis of chiral 4-fluoropolyhydro-2H-chromenes in good yields through a reaction between monoterpenoid alcohols with para-menthane skeleton and aldehydes were developed for the first time. The BF3·Et2O/H2O system is used both as a catalyst and as a fluorine source. The reaction can involve aliphatic aldehydes as well as aromatic aldehydes containing various acceptor and donor substituents. 4-Hydroxyhexahydro-2H-chromenes were demonstrated to be capable of converting to 4-fluorohexahydro-2H-chromenes under the developed conditions, the reaction occurs with inversion of configuration.

Earlier, it was found that the reaction of para‐mentha‐6,8‐diene‐2,3‐diol with 2,4,5‐trimethoxybenzaldehyde in the presence of Montmorillonite K 10 clay led to the formation of a compound with an unusual epoxychromene framework among other products. In the current work, systematic studies of the effect of the number and position of MeO groups in the aromatic ring of the aldehyde on the reaction route were performed to reveal the structural parameters, which favor the formation of compounds with an epoxychromene framework. Compounds with an epoxychromene framework were shown to be formed if the benzaldehyde contained MeO substituents in o‐ and p‐position. The highest yield was achieved in the case of 2,4,5‐trimethoxybenzaldehyde.