A synthetic approach to terpendoles: decahydrobenzo[f]chromenes by an intermolecular Diels-Alder route

Abstract

Synthesis of decahydro-1H-benzo[f]chromene system using intermolecular Diels-Alder reaction has been carried out for the construction of skeleton of terpendole class of terpenoids.

Metal‐Free Organoselenium‐Enabled Radical Relay Azidation‐Carbocyclization

“…Compound 2 a was selectively reduced to give 4 and 5 in excellent yields. These are attractive as valuable cores for further derivatization (Scheme 1b and 1c) [11] . Given the prevalence of azide motifs, further Huisgen [3+2] diversifications of the azide group with 3‐phenylpropiolic acid and ethisterone were performed with 2 a .…”

“…We found that DMSO, which is less volatile and less toxic than CH 3 CN, was the best solvent for this transformation, and its use increased the yield of 2 a to 90%. Other solvents, namely DMF, EtOAc, DCE, 1,4dioxane, and DCM, gave poorer results (Table 1, entries [7][8][9][10][11][12]. In addition, the reaction yield was temperature sensitive and the yield of 2 a decreased to 74% at 60 °C (Table 1, entry 13).…”

“…These are attractive as valuable cores for further derivatization (Scheme 1b and 1c). [11] Given the prevalence of azide motifs, further Huisgen [3 + 2] diversifications of the azide group with 3-phenylpropiolic acid and ethisterone were performed with 2 a. The corresponding triazoles 6 and 7 were obtained in 98% and 97% yields, respectively (Scheme 1d and 1e).…”

Visible Light-Induced Cascade Sulfonylation/Cyclization to Produce Quinoline-2,4-Diones under Metal-Free Conditions

“…In addition, we also expanded the reaction from 1a to 3a on the gram level, and the reaction time was extended to 5 h, which still maintained a high yield of 3a (76%) ( Scheme 1 a). By using 3a as a starting material, the target product 4 could be obtained after sodium borohydride reduction ( Scheme 1 b) [ 31 ]. By using the Cu/NFSI system [ 32 ], efficient conversion of 3a from the tertiary amine to the secondary amine 5 was achieved ( Scheme 1 c).…”