ABSTRACT
New synthetic methods for the construction of novel heterocycles and tryptamines are described. Thus, N-Boc anilines (I) are sequentially converted to heterocycles II ((3-(2-aminophenyl)pyrrolidin-3-ol) derivatives), III (substituted 2-oxo-1,2-dihydrospirobenzo[d][1,3]oxazine-4,3'-pyrrolidines), and VI (2-(4,5-dihydro-1H-pyrrol-3-yl)aniline) derivatives through a route involving t-BuLi induced ortho-metalation/LaCl(3).2LiCl metal exchange, reaction with N-Boc pyrrolidin-3-one (5), and subsequent decarboxylative fragmentation. Labile intermediates VI are effectively converted to tryptamines Xa and Xb under controlled protic acid conditions. In addition to providing expedient access to the 2-oxo-1,2-dihydrospirobenzo[d][1,3]oxazine-4,3'-pyrrolidines (III), the method is applicable to the synthesis of the corresponding 2-oxo-1,2-dihydrospirobenzo[d][1,3]oxazine-4,3'-piperidine series of spirocycles (e.g., 42) and their precursors (3-(2-aminophenyl)piperidin-3-ol derivatives, e.g., 43) by using N-Boc-protected piperidin-3-one (40). Applications of the developed synthetic technologies to the synthesis of regioisomeric spirocycles 87 and 90, tryptamines 88 and 91, Corey's aspidophytine tryptamine (97), and efavirenz (1) are also described.
Subject(s)
Heterocyclic Compounds/chemical synthesis , Tryptamines/chemical synthesis , Heterocyclic Compounds/chemistry , Magnetic Resonance Spectroscopy , Tryptamines/chemistryABSTRACT
The rhodium-catalyzed conjugate addition of functionalized vinyltin reagents to alkylidene Meldrum's acids, followed by Pd-catalyzed intramolecular allylation, is a direct entry into vinyl-substituted gamma-lactones via O-alkylation and vinylcyclopropanes via C-alkylation.
Subject(s)
4-Butyrolactone/analogs & derivatives , 4-Butyrolactone/chemical synthesis , Cyclopropanes/chemical synthesis , Lactones/chemical synthesis , Palladium/chemistry , Rhodium/chemistry , 4-Butyrolactone/chemistry , Alkylation , Catalysis , Cyclopropanes/chemistry , Lactones/chemistry , Molecular Structure , StereoisomerismABSTRACT
A one-pot, two-step process that transforms terminal alkynes into ethyl methyl-substituted benzylic quaternary carbon centers is described. (E)-2,2-Disubstituted-1-alkenyldimethylalanes have been shown to participate in 1,2-alkyl migration from aluminum to carbon with concomitant arylation at the 2-position to furnish ethyl methyl-substituted benzylic quaternary carbon centers, when reacted intramolecularly with aryl halides and triflates in the presence of a Pd(0) catalyst. The protocol is initiated with Cp2ZrCl2-catalyzed methylalumination of terminal alkynes followed by palladium-catalyzed intramolecular arylation of the resulting (E)-2,2-disubstituted-1-alkenyldimethylalanes, leading to 1,2-methyl shift from aluminum to carbon. In that sequence, a total of three new C-C single bonds are made, and two of the three alkyl groups on Me3Al transferred to the substrate on vicinal carbons. This method was applied to a variety of substrates, and the mechanism was investigated by deuterium-labeling experiments, which revealed that protodealumination of the final dialkylaluminum triflate or halide intermediates by CH3CN results in the formation of the fourth bond in the course of the transformation.
