Aldol addition reactions of chiral crotonate imides

Evans, David A.; Sjogren, Eric B.; Bartrolí, Javier; Dow, Robert L.

doi:10.1016/s0040-4039(00)85106-0

Cited by 127 publications

(66 citation statements)

References 19 publications

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“…Subsequent Sharpless epoxidation32 of the allylic alcohol (>18:1 dr) and Parikh-Doering oxidation of the hydroxyl group afforded epoxyaldehyde 23 . Evans aldol reaction33a of 23 with the chiral crotonate imide 24 ,33b silylation of the newly-formed alcohol and reduction of the acyl oxazolidinone with LiBH 4 in aqueous THF34 provided homoallylic alcohol 25a . The primary alcohol of 25a was temporarily protected as a 2-bromoethyl carbonate (BEC); unfortunately, the Alloc group we desired at this position in 6 could not be directly installed due to its incompatibility with subsequent olefin oxidative cleavage steps.…”

Section: Resultsmentioning

confidence: 99%

Total Syntheses of (+)-Tedanolide and (+)-13-Deoxytedanolide

et al. 2008

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Convergent total syntheses of the potent cytotoxins (+)-tedanolide (1) and (+)-13-deoxytedanolide (2) are described. The carbon framework of these compounds was assembled via a stereoselective aldol reaction that unifies the C(1)-C(12) ketone fragment 5 with a C(13)-C(23) aldehyde fragment 6 (for 13-deoxytedanolide) or 52 (for tedanolide). Multiple obstacles were encountered en route to (+)-1 and (+)-2 that required very careful selection and orchestration of the stereochemistry and functionality of key intermediates. Chief among these issues was the remarkable stability and lack of reactivity of hemiketals 33b and 34 that prevented the tedanolide synthesis from being completed from aldol 4. Key to the successful completion of the tedanolide synthesis was the observation that the 13-deoxy hemiketal 36 could be oxidized to C(11,15)-diketone 38 en route to 13-deoxytedanolide. This led to the decision to pursue the tedanolide synthesis via C(15)-(S)-epimers, since this stereochemical change would destabilize the hemiketal that plagued the attempted synthesis of tedanolide via C(15)-(R) intermediates. However, use of C(15)-(S) configured intermediates required that the side chain epoxide be introduced very late in the synthesis, owing to the ease with which the C(15)-(S)-OH cyclized onto the epoxide of intermediate 50.

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Section: Resultsmentioning

confidence: 99%

Total Syntheses of (+)-Tedanolide and (+)-13-Deoxytedanolide

et al. 2008

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“…Our previously developed synthetic approach involving the Evans syn-aldol reaction [9] was employed as the central step for the highly convergent synthesis of 1,5-dienes. [6] Thus, the respective syn-aldol product was obtained in good yield as a single regio-and diastereoisomer starting from crotonyl imide and crotonaldehyde.…”

Section: Preparation Of Oxy-cope Substratesmentioning

confidence: 99%

The Oxy‐Cope Rearrangement of Aldol Products. A Combined Experimental and Theoretical Study

et al. 2012

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The oxy-Cope rearrangement of aldol products has been studied both experimentally and theoretically to gain insight into the aspects that are responsible for the exceptional rate and diastereoselectivity of this process. Kinetic studies as well as DFT calculations convincingly show that the activation barrier of this process is mainly dependent on the electronic nature of the oxy-substituent, with electron-withdrawing O-substituents raising this barrier. The diastereo-

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“…The synthesis began with known alcohol (Ϫ)-19 (10). Swern oxidation, followed by an Evans aldol employing N-acylated oxazolidinone (ϩ)-20 (34,35), provided the aldol adduct as a single stereoisomer. Protection as the diethylisopropylsilyl (DEIPS) ether using freshly prepared DEIPSOTf (36) led to (ϩ)-21 (95% yield).…”

Section: Construction Of the Tedanolide Southern Hemispheresmentioning

confidence: 99%

A unified approach to the tedanolides: Total synthesis of (+)-13-deoxytedanolide

Smith

Adams

Barbosa

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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A unified approach for the construction of the potent marine antitumor agents (؉)-tedanolide (1) and (؉)-13-deoxytedanolide (2) is described. Highlights of the synthetic strategy include the development of a versatile bifunctional dithiane-vinyl iodide linchpin, the unorthodox use of the Evans-Tishchenko reaction, and a late-stage high-risk stereocontrolled introduction of the C(18,19) epoxide to achieve a total synthesis of (؉)-13-deoxytedanolide (2).

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Aldol addition reactions of chiral crotonate imides

Cited by 127 publications

References 19 publications

Total Syntheses of (+)-Tedanolide and (+)-13-Deoxytedanolide

Total Syntheses of (+)-Tedanolide and (+)-13-Deoxytedanolide

The Oxy‐Cope Rearrangement of Aldol Products. A Combined Experimental and Theoretical Study

A unified approach to the tedanolides: Total synthesis of (+)-13-deoxytedanolide

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