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The Enantioselectivity and the Stereochemical Course of Copper‐Catalyzed Intramolecular CH Insertions of Phenyliodonium Ylides
Author(s) -
Müller Paul,
Boléa Christelle
Publication year - 2002
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/1522-2675(200202)85:2<483::aid-hlca483>3.0.co;2-q
Subject(s) - chemistry , ylide , carbenoid , intramolecular force , medicinal chemistry , cyclopentanone , diazo , enantiomer , ethyl diazoacetate , catalysis , insertion reaction , stereochemistry , cyclopropanation , organic chemistry , rhodium
The Cu‐catalyzed intramolecular CH insertion of phenyliodonium ylide 1b was investigated at 0° in the presence of several chiral ligands. Enantioselectivities varied in the range 38–72%, and were higher than those resulting from reaction of the diazo compound 1c at 65°. The intramolecular insertion of the enantiomerically pure methyl diazoacetate ( R )‐ 20 and of the corresponding phenyliodonium ylide ( R )‐ 21 proceeded to ( R )‐ 23 with retention of configuration with [Cu(hfa) 2 ] (hfa=hexafluoroacetylacetone=1,1,1,5,5,5‐hexafluoropentane‐2,4‐dione) and [Rh 2 (OAc) 4 ]. These results are consistent with a carbenoid mechanism for the Cu‐catalyzed insertion with phenyliodonium ylides. However, the insertion of the perfluorosulfonated phenyliodonium ylide ( R )‐ 29 afforded with [Cu(hfa) 2 ] as well as with [Rh 2 (OAc) 4 ] the cyclopentanone derivative 30 as a cis / trans mixture with only 56–67% enantiomeric excess.