Facile Catalyzed Preparation of 14‐Aryl‐ or Alkyl‐14‐H‐dibenzo[a,j]xanthenes by Dodecylphosphonic Acid and Dodecylsulfamic Acid: Environmentally Benign Methods

Abstract

A one‐pot synthesis provides the target compounds under mild‐ and solvent‐free conditions in good to moderate yields.

Camphor-10-sulfonic acid catalyzed condensation of 2-naphthol with aromatic/aliphatic aldehydes to 14-aryl/alkyl-14H-dibenzo[a,j]xanthenes

“…Most catalysts [24][25][26]29 reported so far for the condensation of 1 with aliphatic aldehydes furnished the corresponding dibenzoxanthenes in longer reaction times and in moderate yields. In contrast to benzaldehyde, the CSA catalyzed (10 mol %) condensation of 1 with hexanal (2l) at 25 °C without solvent (24 h) led to complete consumption of starting materials and 14-pentyldibenzoxanthene (4l) was obtained as the sole product in 73 % yield; no trace of 1,1-bis(2-hydroxynaphthyl)hexane was detected (Scheme 2).…”

“…Several methods have been reported for the synthesis of xanthenes and benzoxanthenes, which include trapping of benzynes with phenols, 8 cyclodehydration, 9 cyclocondensation of 2-hydroxyaromatic aldehydes with 2-tetralone 10 and intramolecular phenyl carbonyl coupling reactions of benzaldehydes 1052 KUNDU and NAYAK and acetophenones. 14 Moreover, various catalysts, including TaCl 5 , 15 Sr(OTf) 2 , 16 Yb(OTf) 3 , 17 sulfamic acid, 18 iodine, 19 Amberlyst-15, 20 cyanuric chloride, 21 ceric ammonium nitrate (CAN), 22 27 an ionic liquid, 28 dodecylphosphonic acid (DPA) or dodecylsulfamic acid (DSA), 29 nano-silica phosphoric acid (nano-SPA), 30 nano-SnCl 4 ·SiO 2 , 31 4-dodecylbenzenesulfonic acid (DBSA), 32 tungstophosphoric acid 33 and a functionalized mesoporous material 34 were found to catalyze condensation reactions of 2-naphthol with different aldehydes to afford 14-substituted-14H-dibenzo[a,j]xanthenes. 14 Moreover, various catalysts, including TaCl 5 , 15 Sr(OTf) 2 , 16 Yb(OTf) 3 , 17 sulfamic acid, 18 iodine, 19 Amberlyst-15, 20 cyanuric chloride, 21 ceric ammonium nitrate (CAN), 22 27 an ionic liquid, 28 dodecylphosphonic acid (DPA) or dodecylsulfamic acid (DSA), 29 nano-silica phosphoric acid (nano-SPA), 30 nano-SnCl 4 ·SiO 2 , 31 4-dodecylbenzenesulfonic acid (DBSA), 32 tungstophosphoric acid 33 and a functionalized mesoporous material 34 were found to catalyze condensation reactions of 2-naphthol with different aldehydes to afford 14-substituted-14H-dibenzo[a,j]xanthenes.…”

Efficient one-pot synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives promoted by niobium pentachloride

“…Furthermore, 14-aryl-14H-dibenzo[a,j ]xanthene derivatives can be prepared by the condensation reaction of 2-naphthol with aryl aldehydes in the presence of different Lewis acids (Ding et al, 2007;Wang et al, 2008;Urinda et al, 2009;Wang et al, 2010;Soleimani et al, 2011;Tabatabaeian et al, 2011;Mirjalili et al, 2011;Zolfigol et al, 2012;Rao et al, 2012;Cao et al, 2013) and Brønsted acids (Gong et al, 2009;Hajipour et al, 2010;Rahmatpour, 2011;Ghassamipour & Sardarian, 2012;Zare et al, 2012).…”