Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• dihydropyridinones 49 and 51 in moderate to good yields (45–76%), excellent diastereoselectivities and high enantioselectivities (85–94% ee) (Scheme 18). The reaction was also compatible with 1,1-dialkyl-substituted 3-amidoallylic alcohols 50 as precursors of α,β-unsaturated N–H ketimines; in this case the chiral

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• -4,5-alkyl-substituted pyridines 33 (Scheme 11) [53]. The transformation involved a two-step sequence of successive reactions: Firstly, the nickel-catalyzed [4 + 2]-cycloaddition of 1,3-enynes 31 and N-Ts-substituted 3-azetidinone 30 afforded dihydropyridinones 32 in good yield. The next step involved

• the hydrogenation of dihydropyridinones 32 and a following desulfonylation and aromatization to give pyridine derivatives 33 in moderate to good yield. Synthesis of pyrroles via tandem annulation of 1,3-enynes Recently, great achievements have been made in electrophilic iodocyclization of alkynes for

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• with various heterocyclic C–H acids, resulting in the synthesis of coumarin/quinolinone fused dihydropyranones and dihydropyridinones 47. The reaction optimization and the scope and limitations study were carried out using an achiral NHC, but the enantioselective version was also performed using 4

Rapid, two-pot procedure for the synthesis of dihydropyridinones; total synthesis of aza-goniothalamin

• Thomas J. Cogswell,
• Craig S. Donald and
• Rodolfo Marquez

Beilstein J. Org. Chem. 2020, 16, 135–139, doi:10.3762/bjoc.16.15

• Zealand 10.3762/bjoc.16.15 Abstract A fast, protecting-group-free synthesis of dihydropyridinones has been developed. Starting from commercially available aldehydes, a novel one-pot amidoallylation gave access to diene compounds in good yields. Ring-closing metathesis conditions were then employed to

• produce the target dihydropyridinones efficiently and in high yields. Keywords: amidoallylation; aza-goniothalamin; dihydropyridinones; protecting-group-free; ring-closing metathesis; two-pot procedure; Introduction Six-membered nitrogen heterocycles are prevalent in many naturally occurring and

• biologically active compounds. As a result, their synthesis has received extensive research and wide spread publication in the literature [1][2][3][4][5][6]. Dihydropyridinones are an important subclass of heterocycles, which often feature both as useful intermediates, and as interesting species in their own