A Strategy toward Icetexane Natural Products

Abstract

Icetexane diterpenoids are richly complex polycyclic natural products that have been described with a variety of biological activities. We report here a general synthetic approach toward the 6–7-6 tricyclic core structure of these interesting synthetic targets based on a two-step enolate alkylation and ring-closing metathesis reaction sequence.

Recent Developments with Icetexane Natural Products

“…[98] In 2018, Chain and coworkers attempted to employ their ortho-quinone methide-based methodology to construct the core structure of icetexanes (Scheme 28). [103,104] Exposure of a mixture of the silyl enol ether 193 and the silyloxybenzyl chloride 194 to tetramethylammonium fluoride was successful in inducing a diastereoselective alkylation reaction to give the intermediate 195, however subsequent condensation of the resultant phenol or phenoxide upon the carbonyl function generated the robust hemiacetal 198; neither acidic nor basic reaction conditions could facilitate the isolation of 198 in its open form. Chain and his group addressed this problem by employing a more conventional alkylation reaction strategy.…”

Clickable Azide-Functionalized Bromo-Aryl-Aldehydes – Synthesis and Photophysical Characterization

“…For c): A slightly modified literature procedure was used. [28] A heat gun-dried and nitrogen-flushed Schlenk tube, equipped with a magnetic stirring bar and a rubber septum, was charged with 19 (80.1 mg, 200 µmol, 1.00 eq). The tube was flushed with nitrogen, anhydrous CH2Cl2 (2.00 mL, 0.1 M) was added and the colorless solution was cooled to 0 °C.…”

Clickable Azide-Functionalized Bromo-Aryl-Aldehydes – Synthesis and Photophysical Characterization

“…Quenching processes of triplet states, induced by molecular motions, oxygen or humidity, restrict the versatile application of such organic materials [24]. Thus, low temperatures [25][26][27] or inert conditions [28] are necessary to facilitate afterglow emission.…”

“…Despite multifarious examples of RTP in the crystalline state, purely organic compounds showing RTP in solution are rare [64][65][66][67][68][69]. Takeuchi et al [28] reported a bromofluorenecarbaldehyde 2 which shows blue fluorescence in chloroform at 298 K under air and green phosphorescence under argon with a phosphorescence quantum yield of ΦP = 5.9% (Figure 1b). This observation is reasoned by a strong (π, π*) character of the T2-state.…”