A Route to Vicinal Diamines from the Samarium(II) Iodide-Mediated Coupling of Aldimines

Post‐Assembly Reactivity of N‐Aryl Iminoboronates: Reversible Radical Coupling and Unusual B−N Dynamic Covalent Chemistry

“…Through the addition of an electron abstractor the coupled products selectively and quantitativelyr everted to the iminoboronate startingm aterial, reactivity that is not known in relatedr eductively coupled aldehyde or imine systems. [33][34][35][36][37][38] Using Ph 3 CBF 4 for multiple cycles of coupling and decoupling was not possible due to the reactiono ft he trityl dimer with the iminoboronates upon subsequenta dditions of Cp 2 Co.…”

“…[32] Reductivec oupling reactions involving carbonyls and relatedf unctional groups, such as imines, have received considerable attention for the enantioselective synthesis of fine chemicals and biologically activec ompounds, most notably the SmI 2 -promoted pinacol coupling reaction. [33][34][35][36][37][38] Dostµla nd co-workersr ecently studied the intermolecular reductive coupling of an iminochloroborane with potassium metal in toluene affording an eutral dimer as am ixture of the expected rac-( RR/SS)a nd meso-( RS)d iastereomers. [39] In supramolecular chemistry radicalr eductivec oupling reactions have been exploited for the synthesis of macrocyles, [40][41][42][43] including large macrocyclic hydrocarbons based on spirobifluorenyl units, [44] and stimuli-responsivec yclophanes.…”

“…Solution-statea nalysis of these structures indicated an unprecedented interconversion between the rac 5 and rac 6 isomers by way of al abile BÀNc ovalentb ond at room temperature, establishing as econdary dynamic covalentf eature of the overall system.A dditionally,t he rate of interconversionb etween the two structures was influenced by manipulating the electronic character of the N-containing fragment. Furthermore, the mixture of reductively coupled products could be converted quantitatively back to their iminoboronate precursors by the addition of single-electron abstractor Ph 3 C + .N ot only do these speciesd isplay oxidative decoupling reactivity that is not known for analogous systems( pinacolc oupling [33][34][35][36][37][38] etc. ), this behaviour demonstrates further reversibility in this iminoboronate-based system.…”

“…ATRP) and small molecule syntheses . Reductive coupling reactions involving carbonyls and related functional groups, such as imines, have received considerable attention for the enantioselective synthesis of fine chemicals and biologically active compounds, most notably the SmI 2 ‐promoted pinacol coupling reaction . Dostál and co‐workers recently studied the intermolecular reductive coupling of an iminochloroborane with potassium metal in toluene affording a neutral dimer as a mixture of the expected rac ‐ ( RR/SS ) and meso ‐ ( RS ) diastereomers .…”

“…Furthermore, the mixture of reductively coupled products could be converted quantitatively back to their iminoboronate precursors by the addition of single‐electron abstractor Ph 3 C + . Not only do these species display oxidative decoupling reactivity that is not known for analogous systems (pinacol coupling etc. ), this behaviour demonstrates further reversibility in this iminoboronate‐based system.…”