Olefin alkylpyridines

In Baldwin s formal total synthesis of haliclamines A and B, a Suzuki coupling of 3-bromopyridine was the central operation [52], Chemoselective hydroboration of diene 66 employing 9-BBN occurred at the less hindered terminal olefin. Suzuki coupling of the resulting alkylborane with 3-bromopyridine then furnished alkylpyridine 67 as a common intermediate for the synthesis of haliclamines A and B. 

In a-substituted alkylpyridines of type (69) a molecule of olefin is eliminated very easily, (69)->[70]44 (Biemann,10 p. 130), by a McLaf-ferty rearrangement ... 

The picolyl hydrogens of 2- and 4-alkylpyridines are more acidic than the corresponding benzylic hydrogens. For that reason, the reactions of alkylpyridines with olefins occur under mild ccHiditions, and with conjugated dienes, styrenes, and vinylpyridines at below room temperatures. The mechanism of side-chain addition of alkylpyridines to olefins is very similar to that described for alkylbenzenes. 

Monomeric and polymeric A-alkylpyridine-4-carboxylates serve as redox mediators for the indirect electroreduction of z /c-dihalides to PYWj -olefins [219,220]. 

Pyrinodemin A was reported in 1999 as a cytotoxic pyridine alkaloid isolated from the sponge Amfhimedon sp. collected in Okinawa. The planar structure of this alkaloid was composed of a unique cyclopent[r]isoxazo-lidine connected with a bis-3-alkylpyridine based on the MS and NMR data. Location of the Z olefin [5c 129.3 (2C), C-16 and C-17 ] was assigned from the chemical shift of the two vinyl carbons (C-15 and C-18, ... 

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