Synthesis of spiropyridazine-benzosultams by the [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes

• Wenqing Hao,
• Long Wang,
• Jinlei Zhang,
• Dawei Teng and
• Guorui Cao

Beilstein J. Org. Chem. 2024, 20, 280–286, doi:10.3762/bjoc.20.29

• developed by means of [4 + 2] annulation reaction of 3-substituted benzoisothiazole 1,1-dioxides with 1,2-diaza-1,3-dienes. This approach displays advantages such as mild reaction conditions, wide substrate range tolerance, simple operation, compatibility with gram-scale preparation. Keywords: [4 + 2

• ] annulation reaction; 1,2-diaza-1,3-dienes; spiro-benzosultams; 3-substituted benzoisothiazole 1,1-dioxides; Introduction Spirobenzosultams have various biological activities [1][2][3] such as antiviral, anticancer, antimicrobial, antimalarial, and antileukemia, and are widely used in the pharmaceutical

• ketimines as suitable three-carbon synthons in [3 + 2] and [3 + 3] annulations [11][12][13][14][15]. However, methods using N-sulfonyl ketimines as dienophiles in [4 + 2] annulation reactions to afford biologically important spiro compounds are still limited to date [16]. 1,2-Diaza-1,3-dienes [17][18][19

Multicomponent reactions: A simple and efficient route to heterocyclic phosphonates

• Mohammad Haji

Beilstein J. Org. Chem. 2016, 12, 1269–1301, doi:10.3762/bjoc.12.121

• 4:1 in the presence of 4 Å molecular sieves (Scheme 59) [97]. A sequential three-component enamine–azoene annulation reaction of primary aliphatic amines 292, activated methylene compounds 293, and 1,2-diaza-1,3-dienes (DDs, 294) has been reported to give polysubstituted pyrroles 295 (Scheme 60) [98