Diastereoselective Three‐Step Route to o‐(6‐Nitrocyclohex‐3‐en‐1‐yl)phenol and Tetrahydro‐6H‐benzo[c]chromen‐6‐ol Derivatives from Salicylaldehydes

Abstract

This work was aimed at preparing o-(6Ј-nitrocyclohex-3Ј-en-1Ј-yl)phenol and tetrahydro-6H-benzo[c]chromen-6-ol derivatives in three steps starting from salicylaldehydes. Initially 3-acetylcoumarins were prepared in the absence of solvent using a solid base catalyst such as PS-TBD. In the second step, the Diels-Alder reactions of 3-nitrocoumarins and 3-acetylcoumarins under thermal conditions or in the presence of hafnium chloride yielded the corresponding tetrahydrobenzo[c]chromenones. The final part of the work was dedi-

TBD- or PS-TBD-Catalyzed One-Pot Synthesis of Cyanohydrin Carbonates and Cyanohydrin Acetates from Carbonyl Compounds

“…Polymer-supported catalysts have attracted significant attention in recent decades because of their inherent advantages in synthetic chemistry, e.g., the simplification of reaction procedures including the easy recovery of the catalyst using filtration, application to automated systems, and recycling of the catalyst [68,69,70,71,72,73]. Thus, we examined the cyanomethoxycarbonylation reaction of p -anisaldehydes in the presence of 10 mol % of PS-TBD [63,74,75,76,77,78,79]. The reaction proceeded smoothly and the desired product was obtained in 95% yield after 3 h at room temperature.…”

A Mild and Regioselective Ring-Opening of Aziridines with Acid Anhydride Using TBD or PS-TBD as a Catalyst

“…Polymer-supported catalysts have attracted significant attention in recent decades due to their inherent advantages in synthetic chemistry, e.g., simplification of reaction procedures including easy recovery of the catalyst by filtration, application to automated systems, and recycling of the catalyst [54,55,56,57,58,59]. Some unique reactions have been reported using TBD as an organocatalyst [31,60,61,62,63,64,65]. Thus, we examined the ring-opening reaction of N -tosylaziridine 1a with acetic anhydride in the presence of 10 mol % of PS-TBD.…”

Synthesis of 4-Methoxysalicylaldehyde via Selective Monomethylation of 2,4-Dihydroxybenzaldehyde

“…170-171 °C (lit. 16 169 °C). 1 H NMR (400 MHz, CDCl 3 ) δ 8.49 (s, 1H), 7.55 (d, J = 8.4 Hz, 1H), 6.90 (dd, J = 8.4 Hz, J = 2.4 Hz, 1H), 6.82 (d, J = 2.8 Hz, 1H), 3.92 (s, 3H), 2.70 (s, 3H).…”