Generation and Reactivity of 2-Amido-1,3-diaminoallyl Cations: Cyclic Guanidine Annulations via Net (3 + 2) and (4 + 3) Cycloadditions

Generation and Reactivity of 2-Amido-1,3-diaminoallyl Cations: Cyclic Guanidine Annulations via Net (3 + 2) and (4 + 3) Cycloadditions Total synthesis of (±)-N-methyldibromoisophakellin and N-methylugibohlin via net [3 + 2] cycloguanidinylations employing 2-amido-1,3-diamino-allyl cations Intramolecular (4+3) Cycloadditions of Oxidopyridinium Ions: Towards Daphnicyclidin A Synthesis of Pentahydroxylated Pyrrolizidines and Indolizidines Phosphine‐Catalyzed (4+1) Annulation: Rearrangement of Allenylic Carbamates to 3‐Pyrrolines through Phosphonium Diene Intermediates Dipolar [3+2]-Cycloaddition of Nitrones to 3-Alkoxycarbonyl- and 3-Pivaloyl-Substituted Hetareno[e]pyrrole-2,3-diones Azido and desamino analogs of the marine natural product oroidin Formation of 6-Azaindoles by Intramolecular Diels–Alder Reaction of Oxazoles and Total Synthesis of Marinoquinoline A Enantioselective Synthesis of Tropane Scaffolds by an Organocatalyzed 1,3‐Dipolar Cycloaddition of 3‐Oxidopyridinium Betaines and Dienamines P₄O₁₀/TfOH mediated domino condensation–cyclization of amines with diacids: a route to indolizidine alkaloids under catalyst- and solvent-free conditions