Blue light enhanced Heck arylation at room temperature applied to allenes

Abstract

An unprecedented visible light enhanced room temperature Heck reaction between aryl halides and allenyl tosyl amines is here reported. The simple catalytic system (Pd(OAc)2/PPh3) is exploited to afford arylated vinyl...

Photoinduced Chloroamination Cyclization Cascade with N-Chlorosuccinimide: From N-(Allenyl)sulfonylamides to 2-(1-Chlorovinyl)pyrrolidines

“…Since our previous studies on the reactivity of neutral nitrogen-centered radicals generated from sulfonylhydrazones through photoredox catalysis, , we became interested in other precursors of open-shell intermediates suitable for domino cyclization processes. Recently, we investigated the beneficial effect of blue-light irradiation on a Pd(0) catalyzed reaction between aryl bromides and allenyltosyl amides, thus developing a room temperature Heck reaction to access 2-(1-arylvinyl)­pyrrolidines and piperidines . Similar substrates have already been subjected to haloamination with a brominating reagent (LiBr, NBS or 1-bromopyrrolidin-2-one) in combination with transition metal catalysis, − or with iodine alone .…”

“…Recently, we investigated the beneficial effect of blue-light irradiation on a Pd(0) catalyzed reaction between aryl bromides and allenyltosyl amides, thus developing a room temperature Heck reaction to access 2-(1-arylvinyl)pyrrolidines and piperidines. 31 Similar substrates have already been subjected to haloamination with a brominating reagent (LiBr, NBS or 1-bromopyrrolidin-2-one) in combination with transition metal catalysis, 32 − 34 or with iodine alone. 35 As demonstrated by the recent blooming of chlorination protocols exploiting photoredox catalysis, 36 we envisioned that a light mediated process could have been an ideal approach to tackle this chloroamino cyclization.…”

Inexpensive and bench stable diarylmethylium tetrafluoroborates as organocatalysts in the light mediated hydrosulfonylation of unactivated alkenes

“…have emerged as a sustainable option due to their stability, photocatalytic performances and wide range of useful redox potential. [31][32][33][34][35][36] As part of our ongoing research on the photocatalyzed functionalisation of unsaturated compounds, [37][38][39] we have developed an operationally simple anti-Markovnikov hydrosulfonylation of a broad range of unactivated alkenes 1 with sodium sulfinates 2a-e in the presence of diarylmethylium tetrafluoroborates under purple light (Scheme 1, bottom). This class of compounds is known in the literature as a model substrate in organocatalyzed alkylation reactions [40][41][42][43] or together with benzhydrylium ions have been employed by Mayr as reference electrophiles for the construction of a general basicity scale.…”