Iodine‐DMSO catalyzed chemoselective oxidative aromatization and deallylation, nondeallylation of aryl allyl ether of tetrahydro‐β‐carboline

Abstract

We have developed a simple method for the chemoselective aromatization of tetrahydro-β-carboline with selective nondeallylation O-allyl groups in the presence of iodine (100 mol %) in dimethyl sulfoxide/H 2 O 2 . A convergent approach toward the oxidative aromatization with selective deallylation (deprotection) of O-allyl-tetrahydro-β-carboline using iodine in dimethyl sulfoxide/HCl has been described. The present protocol contains cheap catalyst, easy work up, normal reaction conditions, and high selectivity.

Metal‐Free Iodine‐Catalyzed Oxidative Dehydrogenation of N‐Heterocycles

“…Further increasing the catalyst loading and the temperature did not significantly improve the yield (entries 12–15). Additionally, some additives [9c–e] such as HCl, HOAc or TFA were added to the dehydrogenative system, however no significant beneficial effect was observed (Entries 16–19). Therefore, the reaction conditions screened in Table 1 showed entry 6 was the best reaction condition.…”

“…Despite the advances, the current protocols have been limited to a few special N ‐heterocycles in oxidative dehydrogenative aromatization reactions [9] . For example, the construction of pyridiazin‐3(2 H )‐ones, [9a] carbazoles, [9b] β ‐carbolines, [9c–e] and benzazoles/benzazines [9f] with iodine as promoter have been developed by the Lokhande [9a–e] and Deng groups [9f] (Scheme 1b). Despite these remarkable achievements made, [9] most cases need peroxide/corrosive acid (HCl) [9c–e] or high temperature (160 °C), [9f] thus restricting their potential applications.…”

“…For example, the construction of pyridiazin‐3(2 H )‐ones, [9a] carbazoles, [9b] β ‐carbolines, [9c–e] and benzazoles/benzazines [9f] with iodine as promoter have been developed by the Lokhande [9a–e] and Deng groups [9f] (Scheme 1b). Despite these remarkable achievements made, [9] most cases need peroxide/corrosive acid (HCl) [9c–e] or high temperature (160 °C), [9f] thus restricting their potential applications. Spurred by the above developments of the iodine‐promoted oxidative aromatizations, [8–10] and in continuation of our studies on N ‐heteroarenes synthesis, [12] herein we wish to establish a general and convenient exploration of iodine‐catalyzed oxidative methods for the construction of other new N ‐heteroarene scaffolds.…”

Untitled

“…Initially, we started our strategy for the preparation of diacetyl, hydroxy-indole, methylcyclohexanone derivatives (Scheme 1), (4A-4C). In the present investigation, the synthesis of 2,4-diacetyl-5-hydroxy-3-(1H-indol-3-yl)-5-methylcyclohexanone analogs (Scheme 2, Figure 3) was performed by using modified aldol condensation reactions of heteroaromatic aldehydes and acetylacetone in DMSO solvent yielded intermediate cyclohexanones in excellent yields [32][33] (Scheme 2). When indole-3carbaldehyde was stirred with acetylacetone in the presence of base heterocyclic amine (20 mol%) produce a precursor 1-3 analogs in excellent yields.…”

“…In the pursuit of developing novel antimicrobial agents, herein we demonstrate the preparation of some novel hybrids indazole moiety to investigate their potential antimicrobial activities. Our research group is always interested in finding new heterocyclic compounds for biological testing [25][26][27][28][29][30]. The main objective of our continuous research is to find out new leads molecules with potential antimicrobial activities.…”