Diastereoselective synthesis of tetrahydrofurans via mead reductive cyclization of keto-beta-lactones derived from the tandem Mukaiyama aldol lactonization (TMAL) process.
The development of a diastereoselective, three-step strategy for the construction of substituted tetrahydrofurans from alkenyl aldehydes based on the tandem Mukaiyama aldol-lactonization process and Mead reductive cyclization of keto beta-lactones is reported. Stereochemical outcomes of the TMAL process are consistent with models established for Lewis acid-mediated additions to alpha-benzyloxy and beta-silyloxy aldehydes while reductions of the five-membered oxocarbenium ions are consistent with Woerpel's models. Further rationalization for observed high diastereoselectivity in reductions of alpha-silyloxy 5-membered oxocarbenium ions based on stereoelectronic effects are posited. A diagnostic trend for coupling constants of gamma-benzyloxy beta-lactones was observed that should enable assignment of the relative configuration of these systems.
Mitchell
T Andrew
TA
Department of Chemistry, Texas A&M University, College Station, TX 77842-3012, USA.
Romo
Daniel
D
D000447:Aldehydes / Q000737:chemistry*; D000475:Alkenes / Q000737:chemistry; D003500:Cyclization; D005663:Furans / Q000138:chemical synthesis*; D007783:Lactones / Q000737:chemistry*; D008956:Models, Chemical; D013237:Stereoisomerism
D000447:Aldehydes; D000475:Alkenes; D005663:Furans; D007783:Lactones; C116609:3-hydroxybutanal