title: Asymmetric Protonation of Cumulenolates: Synthesis of Allenyl Aldehydes Facilitated by an Organomanganese Auxiliary.
abstract: Chiral ammonium salts were used to catalyze the isomerization of organomanganese-complexed alkynyl aldehydes to chiral allenal building blocks in moderate to good enantiomeric excesses. Normally, conjugated alkynyl aldehydes do not isomerize to their thermodynamically less stable allene isomers. However, with a manganese auxiliary in place to promote allene formation, asymmetric protonation of cumulenolate intermediates was realized using a variety of cinchonidinium salts in a weakly basic biphasic reaction system. Optimal results were realized using a novel cinchonidinium geranyl derivative with its C-9 hydroxyl group playing a crucial role in enantioselectivity.
authors.affiliation: Department of Chemistry, Florida Atlantic University , Boca Raton, Florida 33431-0991, United States.
authors.forename: Animesh
authors.initials: A
authors.lastname: Roy
authors.affiliation: Department of Chemistry, Florida Atlantic University , Boca Raton, Florida 33431-0991, United States.|CSIR-Medicinal Chemistry Division, Indian Institute of Integrative Medicine , Sanatnagar, Srinagar-190005, India.
authors.forename: Bilal A
authors.initials: BA
authors.lastname: Bhat
authors.affiliation: Department of Chemistry, Florida Atlantic University , Boca Raton, Florida 33431-0991, United States.
authors.forename: Salvatore D
authors.initials: SD
authors.lastname: Lepore
mesh_terms: D000447:Aldehydes / Q000138:chemical synthesis / Q000737:chemistry*; D000466:Alkadienes / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques; D006865:Hydrogenation; D008345:Manganese / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013329:Structure-Activity Relationship
chemical_list: D000447:Aldehydes; D000466:Alkadienes; D009942:Organometallic Compounds; D008345:Manganese; C025947:propadiene