ABSTRACT
Polysubstituted N-H pyrroles with a wide variety of substituents were prepared from vinyl azides and 1,3-dicarbonyl compounds by using Mn(III) complexes as catalysts.
Subject(s)
Azides/chemistry , Carboxylic Acids/chemistry , Manganese/chemistry , Pyrroles/chemical synthesis , Vinyl Compounds/chemistry , Catalysis , Molecular Structure , Pyrroles/chemistryABSTRACT
Two synthetic methods for tetra- and trisubstituted N-H pyrroles are presented: (i) the thermal pyrrole formation by the reaction of vinyl azides with 1,3-dicarbonyl compounds via the 1,2-addition of 1,3-dicarbonyl compounds to 2H-azirine intermediates generated in situ from vinyl azides; (ii) the Cu(II)-catalyzed synthesis of pyrroles from alpha-ethoxycarbonyl vinyl azides and ethyl acetoacetate through the 1,4-addition reaction of the acetoacetate to the vinyl azides. By applying these two methods, regioisomeric pyrroles can be prepared selectively starting from the same vinyl azides.
Subject(s)
Azides/chemistry , Pyrroles/chemical synthesis , Vinyl Compounds/chemistry , Ketones/chemistry , Molecular Structure , Pyrroles/chemistryABSTRACT
The first total synthesis of (-)-sordarin (1) was accomplished exploiting the following key reactions: (i) Ag(I)-catalyzed oxidative radical cyclization of a cyclopropanol derivative leading to a bicyclo[5.3.0]decan-3-one skeleton; (ii) Pd(0)-catalyzed intramolecular allylation reaction resulting in the entire strained bicyclo[2.2.1]heptan-2-one framework of sordaricin (2); (iii) selective dihydroxylation of terminal alkenes by the combined use of OsO(4) and PhB(OH)(2); and (iv) beta(1,2-cis)-selective glycosidation via a 1,3-anchimeric assistance from a 4-methoxybenzoyl group.
Subject(s)
Biochemistry/methods , Indenes/chemical synthesis , Diterpenes/chemical synthesis , Diterpenes/chemistry , Indenes/chemistry , Molecular Structure , StereoisomerismABSTRACT
Primary amines are prepared by the electrophilic amination of Grignard reagents with 4,4,5,5-tetramethyl-1,3-dioxolan-2-one O-phenylsulfonyloxime and the acidic hydrolysis of the resulting imines. [reaction: see text]
ABSTRACT
[reaction: see text] The intramolecular in-plane S(N)2 type reaction of haloalkene E-8a was predicted to be a facile process for the first time by DFT calculations (B3LYP/6-31+G(d),SCRF(dipole, solvent = DMF)) (DeltaG = 14.4 kcal/mol). The prediction was confirmed experimentally. When E-8a was treated with NaH in DMF, benzofuran was obtained in 95% yield. On the other hand, Z-8a was recovered quantitatively even after heating at 110 degrees C.
ABSTRACT
Oxidative addition of oximes to palladium(0) complexes generates alkylideneaminopalladium(II) species, which are utilized as key intermediates for carbon-nitrogen bond formation. Various aza-heterocycles, such as pyrrole, pyridine, isoquinoline, spiroimine, and azaazulene, can be synthesized from O-pentafluorobenzoyloximes having an olefinic moiety via an intramolecular Heck-type reaction (amino-Heck reaction) by treatment with a catalytic amount of a Pd(0) complex.