Synthetic Utility of Arylmethylsulfones: Annulative π-Extension of Aromatics and Hetero-aromatics Involving Pd(0)-Catalyzed Heck Coupling Reactions

Abstract

A straightforward and general method for the synthesis of annulated thiophene, dibenzothiophene, and carbazoles analogues has been achieved involving alkylation of 2-bromo-1-(phenylsulfonylmethyl)arene/heteroarene with arylmethyl bromides/heteroarylmethyl bromides using t-BuOK as a base in DMF, followed by Pd(0)-mediated intramolecular Heck coupling in the presence of KCO in DMF at 80-140 °C. The attractive feature of this protocol is that a wide variety of π-conjugated heterocycles could be readily accessed by an appropriate choice of arylmethylsulfones and benzylic bromides.

Chemistry and Properties of Indolocarbazoles

“…When the annulation reaction was conducted at 110 °C for 4 h, the N-sulfonyl groups remained untouched, providing access to compound 388 (Scheme 86). 192 In a report disclosing preparation and studies of the photoluminescent behavior of an extensive set of fused carbazole derivatives, a single example of an indolo[2,3-c]carbazole, namely compound 389, was reported as a product from the indium-catalyzed cyclization of the 3,3′-biindolyl 390 with methyl propargyl ether (Scheme 87). 513 Following a virtual high-throughput screening toward new materials for OLED devices, the system 391 was identified as a promising candidate.…”

“…Subsequent cyclization in the presence of catalytic amounts of palladium acetate and triphenylphosphine provided a new route to the parent indolo­[3,2- a ]­carbazole 2 (Scheme ). Although this preparative route is inferior compared to an old method for synthesis the unsubstituted system 2 due to the poor atom economy, it may nevertheless have potential in future synthetic applications aiming at, for instance, unsymmetrically substituted derivatives.…”

NMR characterization of rearranged staurosporine aglycone analogues from the marine sponge Damiria sp.

“…These long‐range correlations allowed assignment of damirine A ( 1 ) as an indolo[3,2‐ a ]carbazole fused to an aminoimidazole ring, whereas damirine B ( 2 ) had the same indolocarbazole core fused to an imidazolone moiety. Although the indolo[3,2‐ a ]carbazole scaffold has been generated in prior synthetic studies, [ 6,14 ] it has only rarely been found in a natural product. Damirines A ( 1 ) and B ( 2 ) provide new carbon–nitrogen skeletons not seen in any other reported secondary metabolites, and damirine A ( 1 ) exhibited selective growth inhibitory effects against six different cancer cell lines.…”

Synthesis of Annulated Carbazoles via FeCl3/SnCl4‑Mediated Domino Reaction of Vinyl Ketone Tethered Bromomethylindoles with Arenes and Heteroarenes

“…The annulation of 2-bromomethylindole 9 (0.2 g, 0.48 mmol) with 1,3,5-tri(thiophen-2-yl)benzene (0.170 g, 0.53 mmol) using anhyd SnCl 4 (0.025 g, 0.096 mmol) adopting the general procedure, followed by workup and column chromatographic purification (silica gel, EtOAc/hexane 1:9) gave carbazole 10i as a colorless solid; yield: 0.182 g (63%); mp 128-130 °C. 4, 143.3, 139.5, 139.0, 137.7, 137.4, 136.6, 135.8, 135.4, 133.9, 129.1, 128.2, 128.1, 127.7, 126.5, 125.5 (2 C), 124.2, 124.0, 123.4, 123.0, 120.0, 119.7, 115.3, 114.2, 108 The domino reaction of 2-bromomethylindole 9 (0.20 g, 0.48 mmol) with thienocarbazole 11 17 (0.16 g, 0.52 mmol) using anhyd SnCl 4 (0.025 g, 0.096 mmol) in anhyd 1,2-DCE (10 mL) at rt for 2 h, followed by usual workup and column chromatographic purification (silica gel; EtOAc/hexane 3:97) furnished benzo [b]carbazole 10j as a colorless solid; yield: 0.177 g (63%); mp 144-148 °C.…”