Application of the Tethered Biginelli Reaction for Enantioselective Synthesis of Batzelladine Alkaloids. Absolute Configuration of the Tricyclic Guanidine Portion of Batzelladine B

Autor:	Sylvie K. Ly, Alison S. Franklin, Gilbert H. Mackin, Larry E. Overman, A.J Shaka
Rok vydání:	1999
Předmět:	chemistry.chemical_classification Stereochemistry Organic Chemistry Biginelli reaction Absolute configuration Enantioselective synthesis Batzelladine B chemistry.chemical_compound chemistry Yield (chemistry) Organic chemistry Enantiomer Guanidine Tricyclic
Zdroj:	The Journal of Organic Chemistry. 64:1512-1519
ISSN:	1520-6904 0022-3263
DOI:	10.1021/jo981971o
Popis:	Tethered Biginelli condensation of enantioenriched hexahydropyrrolopyrimidines 8 with beta-ketoesters provides efficient asymmetric access to tricyclic guanidines 9 having a syn relationship of the angular C2a and C8a hydrogens. This reaction was employed to realize the first practical enantioselective access to this fragment of batzelladine alkaloids B (2) and E (5). The efficiency of this strategy is illustrated in the synthesis of the dextrorotatory enantiomer of batzelladine B methanolysis product 10 in 10 steps and 25% overall yield from 2-nonanone and methyl acetoacetate. The asymmetric synthesis of 10 establishes that the absolute configuration of the tricyclic portion of batzelladine B (2) is 25aR,28S,30R. The 4-methyl-7-alkyl-1,2,2a,3,4,5,6,7,8,8a-decahydro-5,6,8b-triazaacenaphthalene-3-carboxylic acid subunit, e.g., 29, of batzelladine alkaloids A (1), D (4), F (6), and G was also prepared for the first time by catalytic hydrogenation of tricyclic guanidines 26 having the 2a,8a-anti stereochemistry.
Databáze:	OpenAIRE
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