Re-Visiting The Diastereoselectivity Of Organocatalytic Conjugate Addition Of 2-Trimethylsiloxyfuran To Trans-Crotonaldehyde

We describe the re-assignment of configuration previously ascribed to product diastereomers resultant from imidazolidinone-catalyzed conjugate addition of 2-trimethylsiloxyfuran to trans-crotonaldehyde. A modified procedure that uses a diphenylprolinol catalyst was subsequently developed to selectively provide the 'syn' diastereomeric product in high enantiomeric excess on decagram scales. (C) 2021 Elsevier Ltd. All rights reserved.