Copper‐Silver Dual Catalyzed Decyanative C–Se Cross‐Coupling

Abstract

Traditionally, a metal‐catalyzed cross‐coupling reaction is governed by displacement of leaving groups such as halogens, tosylates, etc. by different nucleophiles leading to the formation of carbon‐carbon and carbon‐heteroatom bonds. Besides displacement of traditional leaving groups in coupling reactions decyanative cross‐coupling has also received current attention. The objective of this work is to develop a decyanative cross‐coupling through metal‐assisted nucleophilic displacement, which is less explored so far. Thus, a decyanative cross‐coupling of aryl selenocyanate with aryl‐/alkylacetylenes, boronic acids and silanes has been accomplished by a copper‐assisted nucleophilic displacement reaction for an easy access to a series of diaryl, aryl alkyl, aryl vinyl and aryl alkynyl selenides. The best yield of product was obtained using 5 mol% of Cu(OAc)2, Ag2CO3 (20 mol%) and Cs2CO3 (1 equiv.) at 100 °C for 8 h in N‐methylpyrrolidinone (NMP). The advantages of simple operation, high yields and general applicability make this procedure more attractive. A mechanistic pathway has been proposed. Silver plays a key role in the decyanation process. A plausible mechanistic pathway of this decyanative carbon‐selenium cross‐coupling has been proposed based on UV, EPR, HR‐MS and IR analytical data along with results obtained from control experiments.magnified image

C4‐Selective Synthesis of Vinyl Thiocyanates and Selenocyanates Through 3,4‐Dihalo‐2(5H)‐furanones

“…At the same time, similar to thiocyanate derivatives, selenocyanate derivatives also play a good role in many fields for their significant bioactivity and good reactivity . However, compared with the synthesis of vinyl thiocyanate derivatives, the construction of vinyl selenocyanate derivatives is rare,[11d] even recently a three‐component reaction method based on activated alkyne has recently been successfully developed .…”

Intramolecular Hydroamination of Selenoalkynes to 2‐Selenylindoles in the Absence of Catalyst

“…Moreover, all describe the functionalisation of the 3‐position, furnishing 3‐selenylindoles. To the best of our knowledge, there is only one protocol where the authors identified a 2‐substituted selenylindole as a by‐product in a coupling reaction between arylselenocyanate and 2‐ethynylaniline catalysed by Cu(OAc) 2 and Ag 2 CO 3 , in an attempt to synthesise chalcogenoalkynes …”

“…To the best of our knowledge,t here is only one protocol where the authors identified a2 -substituted selenylindole as ab y-product in ac oupling reactionb etween arylselenocyanate and 2-ethynylaniline catalysed by Cu(OAc) 2 and Ag 2 CO 3 ,i na na ttempt to synthesise chalcogenoalkynes. [8] Given the reactivity of the indole ring, and the well-established conditions in functionalisation reactions for the synthesis of 3-selenylindoles, there is clearly al ack of development of new strategies for functionalisation in position 2. With this criterion in mind, and in consonance with our continuing interest in the synthesis of organoselenium compounds, [9] we designed as elenium-containing precursor,c onsidering as ubsequent cyclisation step for indole construction in which the functionalised position was pre-defined.…”

Cross‐Coupling Reactions of Aryltriethoxysilanes and Diaryldiselenides ‐ A New Route for the Synthesis of Diarylselenides

“…Except selenium-based reagents, other coupling partner like organosilanes also have been explored for the said conversion. [27][28] Organosilanes are well known for their applications in Hiyama coupling as they are inexpensive compared to other coupling partners. Apart from it, organosilanes posed a problem of their low reactivity which can be tackled by the use of fluoride source.…”