Gold(I)-Catalyzed Intramolecular Diels–Alder Reaction: Evolution of Trappable Intermediates via Asynchronous Transition States

Abstract

In recent years allenes have been shown to be capable of exhibiting several modes of cycloadditions in the presence of transition metal catalysts that are otherwise unattainable for ethylene and acetylene. Herein, we predict that the [1 + 2]-cycloaddition pathway is accessible in a Au(I)-catalyzed reaction of allene with cis-1,3-butadiene. The electrophilicity of the central carbon of allene can be harnessed using a Au(I)-catalyst and -COOMe mediated stereoelectronics. A potential energy modification approach is applied to stabilize the diradicaloid intermediates. Our simulations establish that the product selectivity of the [4 + 2]- and [2 + 2]-pathways are steered by dynamical effects. Furthermore, a bioinspired version of this reaction is shown to afford an alternative synthetic pathway for proline and azepine analogs indicating rich prospects for thermal allene-butadiene reactions in drug discovery.

Tipping the balance: theoretical interrogation of divergent extended heterolytic fragmentations

“…75,76 Mandal and Datta reported a similarly shaped PES in a gold(I)catalyzed Diels-Alder reaction with a single intermediate well leading to two different products where the product selectivity is steered by dynamic effects. 77 Trajectories originating from TSS(i) ‡ also predominantly form A, with a slightly larger number forming B. Product A is thermodynamically favored, which may manifest in lower energy exit channels from both TSSs on the relatively at energy surface in the vicinity of TSS(i-A) ‡ , Int and TSS(i) ‡ .…”

Gold-Catalyzed Homogeneous (Cyclo)Isomerization Reactions

“…Both the structural architecture of this triatomic system and the electronic nature of the substituents on it direct the metal coordination modes and therefore the reactivity of the activated allene (Figure 1). In addition, the initial mode in which gold coordinates to the cumulenic motif, and the further transformations, determines the spatial disposition of the substituents observed in the isomeric products (Yang and Hashmi, 2014) and even turns the mechanistic pathway away from that of the uncatalyzed reaction (Mandal and Datta, 2018). Interestingly, gold complexes are able to catalyze the racemization of 1,3-disubstituted allenes, a process which has been theoretically studied for the particular case of IPrAuOTf acting as the catalyst (Li et al, 2016).…”

Prediction of the [4 + 2]- and [5 + 4]-cycloaddition reactions in zig-zag carbon nanotubes via an ambimodal transition state: density functional theory calculations

“…18,19 Furthermore, Datta and co-workers reported PES bifurcation in different contexts. 20,21 Single-walled carbon nanotubes (CNTs) are conceptually generated by enfolding of the graphene sheets. Numerous experimental and theoretical studies have been carried out on CNTs to understand their physical, electronic, and optical properties, as well as the chemical reactivity.…”