The Prins Cascade Cyclization Reaction for the Synthesis of Angularly‐Fused Tetrahydropyran and Piperidine Derivatives

Abstract

2‐Arylethylbut‐3‐en‐1‐ol is found to undergo smooth Prins cascade reactions with various aldehydes in the presence of Sc(OTf)3 (10 mol‐%) and a stoichiometric amount of TsOH to afford the corresponding trans‐fused hexahydro‐1H‐benzo[f]isochromenes in good yields with excellent selectivity. Likewise, N‐tosyl‐2‐phenethylbut‐3‐en‐1‐amine gives trans‐fused octahydrobenzo[f]isoquinoline derivatives under similar conditions. This is the first example of the synthesis of hexahydro‐1H‐benzo[f]isochromene and octahydrobenzo‐[f]isoquinoline from 2‐arylethylbut‐3‐en‐1‐ol and N‐tosyl‐2‐phenethylbut‐3‐en‐1‐amine, respectively.

trans-Diastereoselective Syntheses of γ-Lactones by Visible Light-Iodine-Mediated Carboesterification of Alkenes

“…Unless otherwise noted, all reactants or reagents including dry solvents were obtained from commercial suppliers and used as received. Malonate 2a , 30 2b , 31 2c , 32 2d , 33 2f , 3h styrene 1i , 34 1k , 35 1l , 36 and 1-cyclopropyl-1-phenylethyrene 37 were prepared according to the procedure reported.…”

Atom Economical, One-Pot, Three-Reaction Cascade to Novel Tricyclic 2,4-Dihydro-1H-benzo[f]isochromenes

“…14 An intramolecular variation of this reaction with homoallylic alcohols provided a number of tricyclic compounds via an intermediate secondary alkyl carbocation. 15 While a number of fused polycyclic pyran derivatives exist in the literature, this represented a novel approach to their construction, as many other examples use substrates with a preformed ring system. 16 In contrast to these results, the reaction we describe occurs via a putative, high-energy alkenyl cation and includes a subsequent dehydrative aromatization to afford 2,4-dihydro-1 H -benzo[ f ]isochromenes, which also represent a novel class of heterotricycles.…”

“…Recently, a tandem intermolecular Prins/Friedel–Crafts reaction was reported to furnish 4-aryldihydropyrans from homopropargylic alcohols and 4-aryltetrahydropyrans from homoallylic alcohols (Scheme ) when the aromatic compound was used as solvent . An intramolecular variation of this reaction with homoallylic alcohols provided a number of tricyclic compounds via an intermediate secondary alkyl carbocation . While a number of fused polycyclic pyran derivatives exist in the literature, this represented a novel approach to their construction, as many other examples use substrates with a preformed ring system .…”