Organocatalytic (1+4)‐Annulations of MBH Adducts with Electron‐Deficient Systems

Abstract

Benefited from the rapid development of MBH reaction, the reaction of MBH adducts have been established as the most synthetically useful transformations. However, compared with the well‐established allylic alkylations and (3+2)‐annulations, the (1+4)‐annulations of MBH adducts have not developed rapidly until recently. As a helpful complement to the (3+2)‐annulations of MBH adducts, the (1+4)‐annulations of MBH adducts opens a robust access to structurally diverse five‐membered carbo‐ and heterocycles. This paper summarizes recent advances in organocatalytic (1+4)‐annulations using MBH adducts as 1 C‐synthons for the construction of functionalized five‐membered carbo‐ and heterocycles.

Organocatalytic Diastereoselective (4 + 1) Cycloaddition of o-Hydroxyphenyl-Substituted Secondary Phosphine Oxides

“…However, despite these strategies, (4 + 1) cycloadditions of SPOs remain underdeveloped (Scheme d). In fact, (4 + 1) cycloaddition, especially organocatalytic (4 + 1) cycloaddition, is a powerful tool for the synthesis of five-membered heterocycles. , Thus, it is highly valuable to develop organocatalytic (4 + 1) cycloaddition of SPOs for the construction of phosphorus-containing benzo five-membered heterocyclic skeletons.…”

Facile synthesis of 2-vinylindolines via a phosphine-mediated α-umpolung/Wittig olefination/cyclization cascade process

“…9 Among the above elegant organic synthons, MBH carbonates have been recognized as versatile building blocks participating in phosphine-catalyzed annulations. 10 We therefore chose MBH carbonates as the preferred synthons to construct 2-vinylindolines. On the other hand, o -aminobenzaldehydes were employed to forge a variety of benzo-heterocycles, including indolines, dihydroquinolines, quinolines, and benzoazepines.…”

Catalyst-free reaction of 2-(4H-benzo[d][1,3]oxazin-4-yl)acrylates: synthesis of 1,2-dihydroquinolines and 2,3-dihydropyrroles

“…Given the importance of benzoxazine and acrylate units, and in continuation of our efforts on the organocatalytic reactions of MBH carbonates, 18 we have recently successfully developed 2-(4 H -benzo[ d ][1,3]oxazin-4-yl)acrylates as versatile building blocks 19 and realized organocatalytic enantioselective cycloadditions of these synthons with isocyanates, 20 a 2-[aryl(tosylimino)methyl]acrylates, 20 b and 2,4-dihydro-3 H -pyrazol-3-ones, 20 c respectively. To further extend the scope of reaction partners, we herein disclose catalyst-free annulations of 2-(4 H -benzo[ d ][1,3]oxazin-4-yl)acrylates with sulfur ylides and α,β-unsaturated imines, respectively (Scheme 1I).…”