Organocatalytic Michael addition of aldehydes to a β-silylmethylene malonate to form intermediates for the enantioselective synthesis of hydroxylated valerolactones and piperidines

Synthesis of Functionalized Organosilicon Compounds/Distal Ketones via Ring-Opening Giese Addition of Cycloalkanols under Organophotocatalytic Conditions

Visible-light-induced organophotocatalyzed ring-opening followed by remote Giese addition of tertiary cycloalkanols with β-silylmethylene malonates has been developed under mild reaction conditions for the synthesis of organosilicon compounds, bearing a ketone group distally substituted with a silyl group with an additional dialkyl malonate functional handle in moderate to good yields (34-72%). The protocol also worked well with diverse Michael acceptors, such as alkylidene/benzylidene malonates, trifluoro methylidene malonate, benzylidene malononitrile, α-cyano-enone, and α-cyano vinyl sulfone, and delivered desired valuable distally functionalized ketones. To showcase the potential of the method, various synthetic transformations of the obtained product were also demonstrated.

Organocatalyzed enantioselective Michael addition/cyclization cascade reaction of 3-isothiocyanato oxindoles with arylidene malonates

Both enantiomers of functionalized 3,2′-pyrrolidinyl spirooxindoles were obtainedviaa Michael-cyclization cascade reaction using pseudoenantiomeric cinchona alkaloid derived thiourea based bifunctional catalysts.

Cascade reactions: a driving force in akuammiline alkaloid total synthesis

The akuammiline alkaloids are a family of intricate natural products which have received considerable attention from scientists worldwide. Despite the fact that many members of this alkaloid class were discovered over 50 years ago, synthetic chemistry has been unable to address their architectures until recently. This minireview provides a brief overview of the rich history of the akuammiline alkaloids, including their isolation, structural features, biological activity, and proposed biosyntheses. Furthermore, several recently completed total syntheses are discussed in detail. These examples not only serve to highlight modern achievements in alkaloid total synthesis, but also demonstrate how the molecular scaffolds of the akuammilines have provided inspiration for the discovery and implementation of innovative cascade reactions for the rapid assembly of complex structures.