Highly stereoselective nucleophilic addition to cyclopropyl carbonyls: The facial selectivity in the cyclopropyl ketones is opposite to that in the corresponding aldehyde

Nucleophilic addition reaction of Grignard reagents to cyclopropylcarbaldehyde 4 proceeded highly selectively from the si-face to afford 5 in high yield. Although hydride reduction of the corresponding ketone 7 with L-Selectride(R) also proceeded highly diastereoselectively, the facial selectivity was reversed to give the re-Face addition product 5. On the other hand, reduction of 7 with DIBAL-H afforded si-face addition product 6 in high yield. The result suggested that these nucleophilic addition reaction proceeded via either the bisected s-trans or s-cis conformation of the cyclopropane derivatives.