Cryptic post-transition state bifurcations that reduce the efficiency of lactone-forming Rh-carbenoid C–H insertions

Abstract

Post-transition state bifurcations are described that lead to unexpected byproducts in Rh-promoted C–H insertion reactions.

The Dynamics of Chemical Reactions: Atomistic Visualizations of Organic Reactions, and Homage to van ’t Hoff

“…[84,85] These reactions were largely of interestt oorganic community because of the new source of selectivity it provides.T his is widely observed in pericyclic reactions,(shown in Figure 5) including [4+ +2]/[2+ +4] bifurcation as reported by Singleton in the cycloaddition of acrolein with methylvinylketone, [86] and of 3-methoxycarbonylcyclopentadienonet od ifferent dienes; [83] [4+ +2]/[6+ +4] bifurcation reported by Houk in the biosynthesis of Heronamide and SpnF-catalyzedD iels-Alder reactions; [87,88] [6+ +4]/[4+ +6] bifurcations in the cycloadditions of tropone to dimethylfulvene; [89] [4+ +2]/[2+ +2] in the cycloadditions of cyclopentadiene with diphenylketene, [30] and others. [90][91][92][93] In addition, bifurcation phenomenah ave also been found important in other organic reactions, [71] biosynthetic reactions, [94] and organometallic reactions [95,96] as well. These were reviewed thoroughly by Houk, [70] Carpenter [97] and Tantillo.…”

Unified Mechanistic Understandings of Pictet-Spengler Reactions

“…Notably in recent years, direct molecular dynamics simulations [5][6][7][8][9][10][11] have found broad applications in interpreting unusual profiles of organic reactions whose product distribution and stereochemistry are determined by the shape of the potential energy surface (PES) or non-statistical dynamics effects, rather than by the relative heights of energetic barriers, and therefore cannot be well described by classic transition state theory (TST). [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Pictet-Spengler reactions are among the most extensively utilized methods in the synthesis of various indole alkaloids. [30][31][32][33][34] Moreover, their mechanistic aspect is intriguing and has been a topic of intensive research for quite a long time.…”

Tipping the balance: theoretical interrogation of divergent extended heterolytic fragmentations

“…33,[66][67][68] Previous work suggests that IRCs obtained with two different theoretical methods that lead to different products despite originating at ostensibly the same TSS could indicate that a PTSB follows this TSS. [69][70][71] In all dynamics simulations, trajectories were initiated from the DFT-optimized TSSs and propagated in reactant and product directions until structures were reached that closely Fig. 4 Free energy profile (electronic energies in parentheses) and "downhill" dynamics results from B3LYP-D3(BJ) and M06-2X PES's for entry 4 ( Table 1).…”