“…[5] Thea llylborane 2 prepared in this way was used in the first total synthesis of Brevianamide A, ah ighly challenging target for organic synthesis,r eported earlier this year.T his demonstrates the ongoing importance of this class of nucleophiles for organic synthesis. [6] We recently reported reversible H 2 activation by the pyridonate borane 3 that can be described as an intramolecular frustrated Lewis pair (FLP). [7][8][9] Ad istinguishing feature of this system is that the H 2 activation is associated with at ransition of the covalently bound pyridonate substituent to adatively bound pyridone ligand (Scheme 2).…”
Here we report the in situ generation of nucleophilic allylboranes from H2 and allenes mediated by a pyridonate borane that displays frustrated‐Lewis‐pair reactivity. Experimental and computational mechanistic investigations reveal that upon H2 activation, the covalently bound pyridonate substituent becomes a datively bound pyridone ligand. Dissociation of the formed pyridone borane complex liberates Piers borane and enables a hydroboration of the allene. The allylboranes generated in this way are reactive towards nitriles. A catalytic protocol for the formation of allylboranes from H2 and allenes and the allylation of nitriles has been devised. This catalytic reaction is a conceptually new way to use molecular H2 in organic synthesis.
“…[5] Thea llylborane 2 prepared in this way was used in the first total synthesis of Brevianamide A, ah ighly challenging target for organic synthesis,r eported earlier this year.T his demonstrates the ongoing importance of this class of nucleophiles for organic synthesis. [6] We recently reported reversible H 2 activation by the pyridonate borane 3 that can be described as an intramolecular frustrated Lewis pair (FLP). [7][8][9] Ad istinguishing feature of this system is that the H 2 activation is associated with at ransition of the covalently bound pyridonate substituent to adatively bound pyridone ligand (Scheme 2).…”
Here we report the in situ generation of nucleophilic allylboranes from H2 and allenes mediated by a pyridonate borane that displays frustrated‐Lewis‐pair reactivity. Experimental and computational mechanistic investigations reveal that upon H2 activation, the covalently bound pyridonate substituent becomes a datively bound pyridone ligand. Dissociation of the formed pyridone borane complex liberates Piers borane and enables a hydroboration of the allene. The allylboranes generated in this way are reactive towards nitriles. A catalytic protocol for the formation of allylboranes from H2 and allenes and the allylation of nitriles has been devised. This catalytic reaction is a conceptually new way to use molecular H2 in organic synthesis.
“…1B ). 2 For example, Williams and co-workers employed a biomimetic intramolecular Diels–Alder reaction to construct the bicyclo ring system en route to (–)-VM5599, rac -pre-paraherquamide, rac -marcfortine C, and (+) and (–)-versicolamide B (forming C 22 –C 6 and C 4 –C 5 , Fig. 1B ) and recently, Lawrence and co-workers leveraged a similar bioinspired approach to access (+)-brevianamide A.…”
Section: Introductionmentioning
confidence: 99%
“…1B ) and recently, Lawrence and co-workers leveraged a similar bioinspired approach to access (+)-brevianamide A. 2 Notably, a complementary strategy employed by Williams and co-workers featured an intramolecular S N 2′ cyclization in the syntheses of brevianamide B, (–)-paraherquamide A, (+)-paraherquamide B, stephacidins A and B, notoamide B, and avrainvillamide (forming C 22 –C 6 , Fig. 1B ).…”
“…Das dokumentiert die andauernde Bedeutung dieser Klasse von Nukleophilen fürd ie organische Synthese. [6] Wirb erichteten kürzlich, dass das Pyridonatboran 3,d as als intramolekulares frustriertes Lewis Paar (FLP) betrachtet werden kann, in der Lage ist, H 2 reversibel zu spalten. [7][8][9] Ein charakteristisches Merkmal von 3 ist, dass die Wasserstoff-aktivierung mit einer Umwandlung des kovalent gebundenem Pyridonatsubstituentenz ue inem dativ gebundenen Pyridonliganden einhergeht (Schema 2).…”
Wir berichten über die In‐situ‐Darstellung von nukleophilen Allylboranen aus H2 und Allenen durch ein Pyridonatboran, das die Reaktivität eines frustrierten Lewis‐Paares zeigt. Experimentelle und computerchemische Untersuchungen zeigen, dass der kovalent gebundene Pyridonatsubstituent durch die H2‐Aktivierung zu einem dativ gebundenen Pyridonliganden wird. Die Dissoziation des somit gebildeten Pyridon‐Boran‐Komplexes setzt Piers′ Boran frei, was die Hydroborierung eines Allens ermöglicht. Die auf diesem Weg gebildeten Allylborane sind reaktiv gegenüber Nitrilen. Eine katalytische Methode zur Bildung von Allyboranen aus H2 und Allenen und der Allylierung von Nitrilen wurde entwickelt. Diese katalytische Reaktion ist ein konzeptionell neuer Ansatz zur Nutzung von molekularem Wasserstoff in der organischen Synthese.
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