ABSTRACT
The asymmetric total syntheses of hedyosumin E aglycon, 7,10-epoxyhedyosminolide and ent-zedolactone A were realized, with the first two being achieved for the first time.
Subject(s)
4-Butyrolactone/analogs & derivatives , Sesquiterpenes, Guaiane/chemical synthesis , 4-Butyrolactone/chemical synthesis , 4-Butyrolactone/chemistry , Catalysis , Crystallography, X-Ray , Cycloaddition Reaction , Models, Molecular , Sesquiterpenes, Guaiane/chemistry , StereoisomerismABSTRACT
An organocatalytic formal [4 + 2] cycloaddition reaction has been realized that permits rapid access to a wide range of bicyclo[2.2.1]heptane-1-carboxylates in a highly enantioselective manner from simple starting materials under mild and operationally simple conditions.
ABSTRACT
The first and asymmetric total synthesis of hedyosumins A, B, and C was accomplished in 13-14 steps from simple starting materials. The essential tools that allow us to access the tetracyclic skeleton include an organocatalytic [4 + 3] cycloaddition reaction, an intramolecular aldol condensation, and an intramolecular carboxymercuration/demercuration enabled lactonization. A CBS-catalyzed asymmetric reduction was employed to boost the ee of the synthetic natural products to an excellent level. This synthesis established the absolute configurations of hedyosumins A, B, and C.
Subject(s)
Biological Products/chemical synthesis , Drugs, Chinese Herbal/chemical synthesis , Magnoliopsida/chemistry , Sesquiterpenes, Guaiane/chemical synthesis , Aldehydes/chemistry , Biological Products/chemistry , Catalysis , Crystallography, X-Ray , Drugs, Chinese Herbal/chemistry , Molecular Conformation , Molecular Structure , Sesquiterpenes, Guaiane/chemistryABSTRACT
In the title compound, C(21)H(28)N(2)O(4), the dihydro-pyridine ring adopts a flattened boat conformation. The mean plane of the dihydro-pyridine ring and the attached benzene ring form a dihedral angle of 85.1â (1)â Å. One of two ethyl fragments is disordered between two conformations in a 0.67â (4):0.33â (4) ratio. In the crystal structure, mol-ecules related by translation along the a axis are linked into chains via inter-molecular N-Hâ¯O hydrogen bonds.
