Nucleophilic‐Bisphosphine‐Catalysed One‐Pot Sequential [4+2]/[4+2] Annulation of an Allenoate with Benzylidenepyrazolones

Abstract

An efficient bisphosphine‐catalysed sequential [4+2]/[4+2] annulation reaction of a γ‐benzyl allenoate with benzylidenepyrazolones has been developed. Under the catalysis of DPPB [1,3‐bis(diphenylphosphanyl)butane], the [4+2]/[4+2] annulation proceeded smoothly to give spiro‐pyrazolidinone derivatives in moderate yields. This protocol provides a simple and practical strategy for the construction of highly substituted 2H‐spiro[naphthalene‐pyrazole] skeletons.

Correlating structure with ionic conductivity in bis(phosphonium)‐containing [NTf2] thiol–ene networks

“…To prepare bromide precursors 1a and 1b , bis(diphenylphosphino)butane was coupled with either 6‐bromohexene or allyl bromide. The remaining bromide monomers ( 1c – e ) were synthesized by first preparing the Grignard reagent of either 1,4‐dibromobutane or 1,12‐dibromododecane, followed by sequential reaction with diisopropyl‐ or diphenylphosphine chloride and then allyl bromide . This one‐pot procedure was necessary to avoid oxidation in air, particularly for the trialkylphosphines.…”

“…The remaining bromide monomers (1c-e) were synthesized by first preparing the Grignard reagent of either 1,4-dibromobutane or 1,12-dibromododecane, followed by sequential reaction with diisopropyl-or diphenylphosphine chloride and then allyl bromide. 36 This one-pot procedure was necessary to avoid oxidation in air, particularly for the trialkylphosphines. Anion exchange of monomers 1a-e with lithium bis(trifluoromethanesulfonyl)imide resulted in the desired [NTf 2 ] monomers 2a-e.…”

Bismuth(III)-Promoted Trifluoromethylthiolation of Pyrazolin-5-ones with Trifluoromethanesulfenamide

“…Pyrazolin-5-ones have received a great deal of attention because they exhibit important biological properties. 20 Specifically, 5-hydroxyprazoles have found many applications in pharmaceuticals and agrochemicals (Figure 1). 21 Consequently, many methods have been developed for the synthesis of new structurally diverse 5-hydroxyprazole derivatives.…”

Mechanisms of DABCO‐ and DMAP‐catalyzed [2 + 4] cycloaddition reactions of methylallenoate with methyleneindolonone: A DFT study

“…In the experiment, Lewis bases‐promoted annulations of allenoates with activated alkenes, imines, aldehydes, ketones, oxadiene, enynols, and dithioester have been studied. Applications of these annulations in chemical, pharmaceutical, and medical areas have also been achieved . Moreover, Lewis based‐catalyzed annulations of allenoates with many compounds containing polarized C = X (X = C/O/S/N) bonds, such as activated aldehydes, alkenes, ketones, azodicarboxylate, and diazene have also been theoretically reported in the past few decades.…”