Auto‐Tandem Cooperative Catalysis Using Phosphine/Palladium: Reaction of Morita–Baylis–Hillman Carbonates and Allylic Alcohols

Abstract

Auto-tandem catalysis (ATC), in which as ingle catalyst promotes two or more mechanistically different reactions in ac ascade pattern, provides apowerfuls trategy to prepare complex products from simple starting materials. Reported here is an unprecedented auto-tandem cooperative catalysis (ATCC) for Morita-Baylis-Hillman carbonates from isatins and allylic carbonates using as imple Pd(PPh 3 ) 4 precursor.D issociated phosphine generates phosphorus ylides and the Pd leads to p-allylpalladium complexes,a nd they undergo a g-regioselective allylic-allylic alkylation reaction. Importantly,acascade intramolecular Heck-type coupling proceeds to finally furnish spirooxindoles incorporating a4 -methylene-2-cyclopentene motif.E xperimental results indicate that both Pd and phosphine play crucial roles in the catalytic Heck reaction. In addition, the asymmetric versions with either achiral phosphine or chiral auxiliary are explored, and moderate results are obtained.

Unconventional Transformations of Morita–Baylis–Hillman Adducts

“…58 Soon after, Li, Duan and co-workers reported a closely related process under phosphine/palladium dual catalysis for the [4+3] annulation between MBH carbonates 164 and vinylbenzoxazinanones 165 (Scheme 22B). 59 In agreement with Chen's work, 57 the dissociated PPh 3 from the palladium complex is enough to activate the MBH carbonate 164 generating the corresponding nucleophilic P-ylide intermediate. However, the additional use of 30 mol% of PPh 3 increased considerably the reactivity.…”

“…In 2019, Du, Chen and co-workers reported the allylation/Heck cross coupling sequence between isatin-derived MBH carbonates 78 and allyl carbonates 148 via synergistic catalysis (Scheme 21). 57 = Ar) presented good reactivity, affording the racemic spirooxindolic products 149 in moderate to excellent yields. Nevertheless, the alkynyl-and vinylsubstituted counterparts 148 exhibited much lower reactivity, producing the final diene products in lower yields.…”

Cooperative Tertiary Amine/Chiral Iridium Complex Catalyzed Asymmetric [4+3] and [3+3] Annulation Reactions

“…As outlined in Scheme a, apart from generating π‐allylmetal complexes I via Pd 0 or Ir I catalysis, MBH carbonates can be converted to electrophilic salts II or allylic ylides III under the catalysis of Lewis bases (LBs), such as tertiary phosphines and amines. Recently, we first accomplished the chemoselective activations of MBH carbonates from isatins and simple allylic carbonates under the cooperative catalysis of phosphines and Pd 0 . We envisaged that the assembly of zwitterionic allylic ylides III and metal‐containing 1,4‐dipoles IV might provide access to fundamentally new transformations (Scheme b).…”

Recent Advances in the Development of Catalytic Methods that Construct Medium-Ring Lactams, Partially Saturated Benzazepines and Their Derivatives

“…Chen and co-workers reported a modular asymmetric [4+3] annulation to construct spirocyclic azepines from Morita-Baylis-Hillman carbonates 57 and 1-azadienes 58 (Scheme 11). 30 The success of the author's annulation strategy required the chiral amine catalyst to react with 57 to generate allylic ylide 61. Addition to 58 forms 62, which cyclizes to afford the spirocyclic N-heterocycle 60.…”