1998
DOI: 10.1021/jo972255+
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Assembly of 3a-Arylperhydroindoles by the Intramolecular Cycloaddition of 2-Azaallyl Anions with Alkenes. Total Syntheses of (±)-Crinine, (±)-6-Epicrinine, (−)-Amabiline, and (−)-Augustamine

Abstract: The 2-azaallyl anion route to pyrrolidines was used for the concise synthesis of alkaloids featuring the 3a-arylperhydroindole nucleus. The brevity and efficiency of the syntheses described are particularly notable. The key transformations involved the tin−lithium exchange of (2-azaallyl)stannanes to 2-azaallyl anions, which participated in intramolecular [π4s + π2s] cycloadditions with styrenes to produce the requisite 3a-arylperhydroindoles. (±)-Crinine was synthesized in eight steps in 20% overall yield, wi… Show more

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Cited by 54 publications
(29 citation statements)
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References 24 publications
(36 reference statements)
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“…Fortunately, cleavage of the amide by treatment with NaOEt in ethanol delivered the cyclization product 27. [11] Finally, reduction of 27 with NaBH 4 furnished the target molecule, whose structure was confirmed by X-ray analysis. [11] Because the analytical data of our synthetically obtained gracilamine were in agreement with those reported for naturally ocurring gracilamine, we could fully establish the relative configuration of gracilamine (Scheme 6).…”
mentioning
confidence: 95%
“…Fortunately, cleavage of the amide by treatment with NaOEt in ethanol delivered the cyclization product 27. [11] Finally, reduction of 27 with NaBH 4 furnished the target molecule, whose structure was confirmed by X-ray analysis. [11] Because the analytical data of our synthetically obtained gracilamine were in agreement with those reported for naturally ocurring gracilamine, we could fully establish the relative configuration of gracilamine (Scheme 6).…”
mentioning
confidence: 95%
“…Examples include the total synthesis of crinine [12,13], amabiline [13,14] mine [13,14], and an approach to 6a-epipretazettine [15]. Three additional examples of these efforts are briefly described below.…”
Section: -Azaallyllithium Cycloadditionsmentioning
confidence: 99%
“…55,56 The aldehyde 121 was prepared in optically active form in only a few steps from the commercially available acetonide of D-erythronolactone. As shown in Scheme 29, we were able to achieve the first total syntheses of these compounds.…”
Section: Amabiline and Augustaminementioning
confidence: 99%
“…56,58 The necessary (2-azaallyl)stannane 146 was formed from the alcohol 145 by a Swern oxidation followed by condensation with (aminomethyl)tri-n-butyl stannane. 56,58 The necessary (2-azaallyl)stannane 146 was formed from the alcohol 145 by a Swern oxidation followed by condensation with (aminomethyl)tri-n-butyl stannane.…”
Section: Crinine and 6-epicrininementioning
confidence: 99%