Stereoretentive O-to-C rearrangement of vinyl acetals: solvent cage effects as a stereocontrol element.
The Lewis acid-mediated rearrangement of chiral vinyl acetals may be induced to provide the product of stereoretention using Me3Al and BF3.OEt2 in concert. The selectivities obtained in this reaction (86:14 to 96:4) are complementary to that observed when relying on oxocarbenium facial bias to control the newly formed stereocenter. Evidence is presented that this reaction occurs by tight ion-pair binding in the solvent cage. The relay of C-O bond stereochemistry to a C-C bond stereocenter via ionic intermediates is an addition to similar established methods such as the Claisen rearrangement.
Zhang
Yongda
Y
Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA.
Reynolds
Nathan T
NT
Manju
Kavita
K
Rovis
Tomislav
T
D000080:Acetals / Q000737:chemistry*; D004988:Ethers, Cyclic / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013237:Stereoisomerism; D014753:Vinyl Compounds / Q000737:chemistry*
D000080:Acetals; D004988:Ethers, Cyclic; D012997:Solvents; D014753:Vinyl Compounds