Aza-bicyclic alkenes

Note added in proof. ktotA synthesis of (-)-xialenon A using bicyclic alcohol 77 [Eq. (26)] represents the first application of enantioselective a-hthiation transannular C-H insertion of epoxides in natural product synthesis [78]. The first enantioselective generation - intermo-lecular nucleophile trapping of a lithium carbenoid has been described, via enantioselective a-deprotonation of the epoxides of oxa- and aza-bicyclic alkenes [e.g. 93 Eq. (30)] using alkyl-lithiums in the presence of (-)-sparteine or bisoxazoline 5 [Eq. (3)] [79]. Insertion of a second... 

Iron Complexes of EeCl3 with ort/io-phenylene diphosphine ligands have been reported to catalyse a yn-diastereoselective carbometallation of oxa- and aza-bicyclic alkenes (88) with ArjZn. The intermediate organometallics (89), in which -elimination is precluded, can be trapped by electrophiles to produce adducts (90)160 jjj jjjg oiat described for the Pd-catalysed carbozincation of 0... 

Ring-Opening Unsymmetrical Oxa- and Aza-bicyclic Alkenes with Heteroatom Nucleophiles 427 Y = halide or excess ligand... 

Zhang L, Le CM, Lautens M (2014) The Use of silyl ketene acetals and tmol ethers in the catalytic enantioselective alkylative ring opening of oxa/aza bicyclic alkenes. Angew Chem... 

Grubbs and coworkers [238] used the ROM/RCM to prepare novel oxa- and aza-heterocyclic compounds, using their catalyst 6/3-15 (Scheme 6/3.9 see also Table 6/3.1). As an example, 6/3-35 gave 6/3-36, by which the more reactive terminal alkene moiety reacts first and the resulting alkylidene opens the five-membered ring. In a similar reaction, namely a domino enyne process, fused bicyclic ring systems were formed. In this case the catalyst also reacts preferentially with the terminal alkene moiety. 

Reactions of nitrones 54 incorporating the homoadamantane skeleton with alkenes lead to 2-aza-3-oxatetracyclo 7.3.1.1. ()2-6j.tetradecanes, c.g.,55, with dimethyl fumarate <97T5413>. Intramolecular cycloaddition to give the bicyclic isoxazolidine 57 occurs with high stereoselectivity when the nitrone 56 is heated <96SL1215>. 

In this reaction, the tethered alkene functionality of the aniline derivatives form a Tr-allyl complex with the Pd(II) catalyst, and then the cyclization takes place via intramolecular nucleophilic attack by the N to form another Pd-complex, which reacts with CO as the electrophilic carbon source in the presence of MeOH to afford substituted bicy-clic pyrrolidine derivatives. However, these products were not stereoselective in nature. A similar type of Pd-catalyzed nonstereoselective cyclizations were also reported by Weinreb et al. and by Larock and Yang for the construction of bicyclic and bridged aza-cycles." ... 

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