A Gold(I)‐Catalyzed Oxidative Rearrangement of Heterocycle‐Derived 1,3‐Enynes Provides an Efficient and Selective Route to Divinyl Ketones

Abstract

The gold‐catalyzed oxidation of N‐tosyl‐protected 6‐alkynyl‐3,4‐dihydro‐2H‐pyridines was studied in detail to obtain divinyl ketones in which one of the double bonds is embedded in a heterocyclic framework. The best reaction conditions were then extended to different types of substrates to assess the scope of the reaction. DFT calculations were exploited to gain insight into the regio‐ and chemoselectivity of the process too. The obtained divinyl ketones were then easily cyclized by a Nazarov process and the bi‐ or polycyclic compounds used as scaffolds in the synthesis of analogues of the plant hormones strigolactones.

Homogeneous Gold-Catalyzed Oxidation Reactions

“…In 2017, Prandi reported the use of enynes as substrates, leading to the formation of dialkenyl ketones (Scheme 41C). 117 Good regioselectivity was achieved in all cases, and the general preference was in accordance with the previous study by L. Zhang (see Scheme 40A). 112,116 Interestingly, the authors found that the DFT-calculated enthalpy values of the two regioisomeric gold carbenes were not always in agreement with the reaction outcome, suggesting the presence of an entropic influence in the reaction.…”

Mechanistic Elucidation of Gold(I)-Catalyzed Oxidation of a Propargylic Alcohol by a N-Oxide in the Presence of an Imine Using DFT Calculations

“… Due to the high electrophilicity of the resultant carbene species, they are subject to internal/external nucleophilic attacks. For example, gold-catalyzed oxidation of internal alkynes by N-oxides gives carbenes, which can be trapped by three different routes to yield different intermediates/products as outlined in Scheme . − …”

From synthetic control to natural products: a focus on N‐heterocycles

“…1), 16 used as substrates in the Suzuki-Miyaura reaction with vinyl boronates 17,18 and alkoxydienylboronates, [19][20][21][22][23] in alkoxycarbonylations, [24][25][26][27] the synthesis of Weinreb amides, 28 or in Sonogashira couplings. [29][30][31] In this review, we report on the synthetic value of this approach using selected examples that emphasize the potential of this methodology for the stereoselective synthesis of N-derived natural compounds and their analogues.…”

“…Lactam‐derived vinyl triflates and phosphates can be used as coupling partners in Pd(0)‐catalysed reactions to be converted into lactam‐derived boronates (Fig. ), used as substrates in the Suzuki–Miyaura reaction with vinyl boronates and alkoxydienylboronates, in alkoxycarbonylations, the synthesis of Weinreb amides, or in Sonogashira couplings . In this review, we report on the synthetic value of this approach using selected examples that emphasize the potential of this methodology for the stereoselective synthesis of N ‐derived natural compounds and their analogues.…”