Stereo- and regioselectivity of Pd(0)/InI-mediated allylic additions to aldehydes and ketones. In situ generation of allylindium(III) intermediates from N-acylnitroso Diels-Alder cycloadducts and 1-amino-4-acetoxycyclopentenes.
Acylnitroso Diels-Alder cycloadduct (11, 37, and 45)- and cyclopentenyl acetate (8 and 9)-derived allylindium(III) species were generated in situ from palladium(0) catalysts and indium(I) iodide, and the stereo- and regiochemistry of their additions to aldehydes and ketones were investigated. Solvent, catalyst, and ionic effects were examined for the reaction of N-acetyl cycloadduct (11) and benzyloxyacetaldehyde (10). The solvent mixture of THF/H(2)O with Pd(OAc)(2).PPh(3) catalysis was found to be optimal. The addition of N-acetyl cycloadduct to aliphatic aldehydes afforded products in good yields and high regio- and stereoselectivity, with the cis-1,4-isomers constituting 90-95% of the products. The reactions with N-Boc (37a) and N-methylcarbamate (37b) cycloadducts also gave the cis-1,4-products predominantly. The same regio- and stereoselectivity applied to the reactions of 4-acetoxy-1-(N-hydroxyphenyacetamido)cyclopentene (8). 4-Acetoxy-1-phenylacetamidocyclopentene (9), however, afforded trans-1,4-products exclusively. Mechanistic speculations involving chelated transition states are described.
Lee
Wenlin
W
Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA.
Kim
Kyung-Hee
KH
Surman
Matthew D
MD
Miller
Marvin J
MJ
D000447:Aldehydes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis*; D007204:Indium / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009603:Nitroso Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D013237:Stereoisomerism
D000447:Aldehydes; D003517:Cyclopentanes; D007659:Ketones; D009603:Nitroso Compounds; D007204:Indium; D010165:Palladium