Unveiling the Three-Component Phosphonylation on Alkynylaldehydes: Toolbox toward Fluorescent Molecules

Abstract

A regioselective tandem approach for annulated napthyridines/isoquinolines embedded with the phosphine oxide group under mild reaction conditions has been achieved in good to excellent yields. The designed strategy involves the triflateinduced formation of new C sp 3 −P and C sp 2 −N bond formation in one pot. This protocol was also well tolerated for the construction of densely functionalized organo-phosphorylated chromenes in good yields. Further, phosphino-derived sulfamethazine and sulfamethoxazole drugs were also successfully synthesized in good yields. The mechanistic studies revealed that the ionic pathway and the formation of regioselective 6-endo dig cyclized products were confirmed through X-ray crystallographic studies. Interestingly, photophysical studies of selectivity selected compounds revealed their stimulating fluorescence properties.

Harnessing the Reactivity of ortho-Alkynylaldehydes: Silver Triflate Catalyzed Regioselective Synthesis of Phosphonylated Fluorescent Molecules

“…Recently, we reported a three-component cyclization of o -alkynylaldehyde with anilines and diphenylphosphine oxides under mild conditions (Scheme 1c ). 22 The reaction proceeds via regioselective 6- endo -dig cyclization to yield phosphonylated naphthyridines, isoquinolines, and chromene derivatives in the presence of a silver catalyst. Inspired by previous reports and our ongoing work on o -alkynylaldehydes, 23 we report here a silver-catalyzed regioselective 5- exo -dig cyclization of o -alkynylaldehydes in the presence of a silver catalyst to yield phosphonylated 1,3-dihydrofuro[3,4- b ]quinolines and dihydrofuro[3,4- b ]pyridines (Scheme 1d ).…”

Synthesis of 6H-Chromeno[4,3-b]quinolin-7-ylphosphonates through Three Component Phosphonylation of Coumarin Carbaldehyde and Their Antimicrobial and Photophysical Properties

“…On the other hand, construction of small molecules including phosphonate groups at cyclic amines is of particular significance in organic chemistry. 9 Coumarins with natural and synthetic origin are important compounds that have various pharmacological and biological activities. 10−12 Such properties of coumarin derivatives are dependent on the substitution position and pattern.…”

“… , Recently, aminophosphonate derivatives embedded in heterocyclic frameworks have shown interesting biological and physical activities. − It seems that the presence of heterocyclic parts in the molecular structure of the aminophosphonates has a significant effect on their biological and optical properties. On the other hand, construction of small molecules including phosphonate groups at cyclic amines is of particular significance in organic chemistry …”

An environmentally benign and atom-economical protocol for the regioselective synthesis of isoquinolones from o-alkynylaldehydes

“…The synthesis of isoquinolones from ortho -alkynylbenzaldehydes using aliphatic amino alcohols has remained elusive. Considering the notable lack of procedures and in continuation of our ongoing work 19 using ortho -alkynyl benzaldehydes, herein we report an environmentally benign, transition metal- and base-free, atom-economical protocol for the synthesis of the privileged isoquinolone scaffold via regioselective intramolecular iodoamidation of alkynes under mild conditions. The present methodology is advantageous over the hitherto known strategies as, here, the free-OH group remains intact and is readily accessible for subsequent transformation.…”