Enantiomerically pure alpha-amino acid synthesis via hydroboration-suzuki cross-coupling.
The Garner aldehyde-derived methylene alkene 5 and the corresponding benzyloxycarbonyl compound 25 undergo hydroboration with 9-BBN-H followed by palladium-catalyzed Suzuki coupling reactions with aryl and vinyl halides. After one-pot hydrolysis-oxidation, a range of known and novel nonproteinogenic amino acids were isolated as their N-protected derivatives. These novel organoborane homoalanine anion equivalents are generated and transformed under mild conditions and with wide functional group tolerance: electron-rich and -poor aromatic iodides and bromides (and a vinyl bromide) all undergo efficient Suzuki coupling. The extension of this methodology to prepare meso-DAP, R,R-DAP, and R,R-DAS is also described.
Collier
Philip N
PN
Department of Chemistry, University of York, Heslington, York YO10 5DD, UK.
Campbell
Andrew D
AD
Patel
Ian
I
Raynham
Tony M
TM
Taylor
Richard J K
RJ
D000596:Amino Acids / Q000138:chemical synthesis* / Q000737:chemistry*; D001959:Bromates / Q000737:chemistry*; D002384:Catalysis; D002625:Chemistry, Organic / Q000379:methods*; D002855:Chromatography, Thin Layer; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism
D000596:Amino Acids; D001959:Bromates; D010165:Palladium