Palladium-catalyzed asymmetric addition of pronucleophiles to allenes
Publikation: Beitrag in Fachzeitschrift › Forschungsartikel › Beigetragen › Begutachtung
Beitragende
Abstract
Simple additions are the most atom economic way to effect alkylations. The ability to effect the hydrocarbonation of allenes asymmetrically then becomes a highly efficient alkylation protocol. The first example of such a protocol involves the ability of a palladium(0) catalyst derived from palladium trifluoroacetate dimer and the bis-2-diphenylphosphinobenzamide of trans-1,2-diamininocyclohexane to catalyze additions to benzyloxyalkene. Various substituted Meldrum's acids including hydroxy Meldrum's acid react well in the presence of 1 mol % trifluoroacetic acid to give one regioisomer with ee's ranging from 82 to 99%. Switching to azlactones to access unusual quarternary amino acids requires somewhat more basic conditions. Thus, use of 2 mol % potassium α-butoxide and 20 mol % hippuric acid leads to a smooth reaction to produce a simple regiosomer. This nucleophile raises the question of facial selectivity with respect to both the nucleophile and the electrophile. Excellent diastereoselectivity (dr 13-20:1) and enantioselectivity (85-94% ee) are obtained. Thus, a new approach for asymmetric allylic alkylations of carbon pronucleophiles by simple additions provides a very efficient, more atom economic strategy for asymmetric C-C bond formation.
Details
Originalsprache | Englisch |
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Seiten (von - bis) | 4438-4439 |
Seitenumfang | 2 |
Fachzeitschrift | Journal of the American Chemical Society |
Jahrgang | 125 |
Ausgabenummer | 15 |
Publikationsstatus | Veröffentlicht - 16 Apr. 2003 |
Peer-Review-Status | Ja |
Extern publiziert | Ja |
Externe IDs
PubMed | 12683811 |
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ORCID | /0000-0001-8423-6173/work/171062644 |