Diastereoselective reduction of an α-keto-ester derived from (−)-8-phenylmenthol: A 4-step synthesis of R-Halostachine analogue.

Solladié‐Cavallo, Arlette; Bencheqroun, M.

doi:10.1016/s0957-4166(00)82014-5

Cited by 28 publications

(1 citation statement)

References 10 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One reason for this may be that the RCONO species are very short-lived and hence spectroscopically undetectable . However, in the case of 8-phenylmenthyl glyoxalates, the glyoxalate moiety has been proved to lie in the s-cis arrangement, wherein π attractive interaction is presumed to hold the two carbonyl groups in the s-cis conformation . A similar situation should be expected for the acylnitroso compounds 13a − f , whose structural and electronic features are similar to those of the 8-phenylmenthyl glyoxalates, to show the s-cis preference in the cyclization of transition state 16 .…”

Section: Resultsmentioning

confidence: 82%

Total Synthesis of (−)-Epibatidine Using an Asymmetric Diels−Alder Reaction with a Chiral N-Acylnitroso Dienophile

1998

View full text Add to dashboard Cite

An asymmetric total synthesis of (−)-epibatidine (1), isolated from the skin of the Ecuadorian poison frog, Epipedobates tricolor, of the family Dendrobatidae, has been achieved by virtue of the development of asymmetric hetero Diels−Alder (D−A) cycloaddition with an N-acylnitroso dienophile bearing the optically active 8-arylmenthol as a chiral source. Thus, in situ oxidation of the hydroxamic acid ent-12f incorporating the (1S,2R,5S)-8-(2-naphthyl)menthyl auxiliary was performed using the Swern conditions to produce the acylnitroso dienophile, which reacted at once with 2-chloro-5-(1,5-cyclohexadienyl)pyridine (7) to provide the (1S,4R)-meta-aza cycloadduct 24 as a major diastereoisomer. The observed facial diastereoselectivity is consistent with a transition-state model with the naphthyl group in “stacked” position and with the acylnitroso group in the s-cis conformation, wherein π attractive interaction between the naphthyl and nitrosocarbonyl groups may contribute to facial control. Compound 24 underwent hydrogenation followed by removal of the chiral auxiliary with LiH2NBH3 and reductive cleavage of the N−O bond with Mo(CO)6 to give the amino alcohol derivative 29, which was converted to (−)-epibatidine via bromination followed by cyclization.

show abstract

Section: Resultsmentioning

confidence: 82%