ABSTRACT
[reaction: see text] The preparation of (+/-)-24, a model for the core of the zaragozic acids, is reported. The pivotal reaction in this endeavor is the dirhodium(II)-catalyzed intramolecular C-H bond insertion of 2-diazoacetyl-1,3-dioxane 4, a transformation which generates four of the six stereocenters present in the core structure. A novel method for the diastereoselective synthesis of pyruvic acid acetals was also developed and employed in the preparation of 4 from xylitol derivative 7.
Subject(s)
Bridged Bicyclo Compounds, Heterocyclic/chemical synthesis , Octanes/chemical synthesis , Tricarboxylic Acids/chemical synthesisABSTRACT
[reaction: see text] The formal synthesis of (+/-)-desmethylamino FR901483 (2) is described. Construction of the unique azatricyclic skeleton of 2 was accomplished by a sequence which involved (i) preparation of dienone 7 by an N-methoxy-N-acylnitrenium ion-induced spirocyclization, (ii) formation of 2-azabicyclo[3.3.1]nonane 5 by the 6-(pi-exo)-exo-trig radical cyclization of 1,7-enyne 6, and (iii) installation of the C-5 p-methoxybenzyl side chain by Lewis acid-mediated alkylation of silyl enol ether 18.
Subject(s)
Aza Compounds/chemistry , Bridged Bicyclo Compounds, Heterocyclic/chemistry , Bridged-Ring Compounds/chemistry , Immunosuppressive Agents/chemical synthesis , Organophosphorus Compounds/chemical synthesis , Spiro Compounds/chemistryABSTRACT
[structure: see text]. A formal synthesis of the muscarinic M(1) receptor antagonist (-)-TAN1251A (7) from L-tyrosine is described. Central to this venture has been the construction of the 1-azaspiro[4.5]decane skeleton present in the natural product by an N-methoxy-N-acylnitrenium ion-induced spirocyclization. The dienone generated in this transformation, 10, was converted to (-)-TAN1251A via tricycle 9, an intermediate in Kawahara's recent synthesis of racemic 7.
