X=Y-ZH systems as potential 1,3-dipoles. Part 34. generation of nitrones from oximes. Tandem michael addition-1,3-dipolar cycloaddition reactions. class 2 processes utilising bifunctional michael acceptor-dipolarophile components.

7‐Oxa‐4‐thia‐1‐aza‐bicyclo[3.2.1]octane 4,4‐Dioxides: Mechanochemical Synthesis by Tandem Michael Addition–1,3‐Dipolar Cycloaddition of Aldoximes and Evaluation of Antibacterial Activities

“…Formation of other products, for example 7‐aryl/alkyl‐8‐oxa‐4‐thia‐1‐aza‐bicyclo[3.2.1]octane 4,4‐dioxides 5 was not observed. Grigg et al, Padwa et al,[4e], [4f] and Hota et al separately reported that nitrones 3 derived from the corresponding aldoximes 2 undergo 1,3‐dipolar cycloaddition in regio‐ and stereospecific manner to afford bridged heterocycles 4 only under different reaction conditions (both conventional media and aqueous media). It seems that a similar pathway is followed under the mechanochemical conditions as well.…”

“…The spectra are in good agreement with the reported values of the known compounds. [4a], [4b], [4c], [4e], [4f], The appearance of a doublet at around 4.5 ppm in the 1 H NMR spectrum (peak of exo ‐H at C‐6) and not in the range of δ = 2.4–2.7 ppm clearly indicates the presence of –OCH 2 – (and not aliphatic –CH 2 –) affirming formation of the 7‐oxa‐bicyclo[3.2.1]octane ring system. In the 13 C NMR spectrum the corresponding carbon peak appeared at δ = 68–70 ppm and not in the aliphatic zone.…”

“…On the other hand, scaffolds like aza‐bicyclo[3.2.1]octane and oxa‐aza‐bicyclo[3.2.1]octane are ubiquitous among various bioactive compounds , . Of our interest, somewhat complex bridged bicyclic sulfone derivatives, namely 7‐oxa‐4‐thia‐1‐aza‐bicyclo[3.2.1]octane 4,4‐dioxides are known in the literature but not much is known about their bioactivities. These sulfone derivatives are mainly constructed by tandem Michael addition–1,3‐dipolar cycloaddition of oximes, a method separately reported by Grigg and Padwa.…”

“…These sulfone derivatives are mainly constructed by tandem Michael addition–1,3‐dipolar cycloaddition of oximes, a method separately reported by Grigg and Padwa. [4e], [4f] While these conventional methods are disadvantageous because of toxic solvents and high temperatures, only one “green” method is available involving a reaction in aqueous micellar media …”

Enantioselective N‐Heterocyclic Carbene Catalyzed Cyclopentene Synthesis via the β‐Azolium Ylide

“…The reaction generality was examined through variation of the two Michael‐acceptor groups (E 1 and E 2 ) and the R substituents (Table ). Substrates were prepared, using the previously described procedure or, in the case of 8 e – h , by Wittig reaction of a known aldehyde precursor . The cycloisomerization proved robust, with 17 cyclopentenes ( 9 a – q ) prepared in good yield and with high enantiopurity.…”