Studies toward the Total Syntheses of Cucurbitacins B and D

Jung, Michael E.; Lui, Rebecca M.

doi:10.1021/jo101242e

Cited by 19 publications

(8 citation statements)

References 36 publications

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“…This DA approach was originally identified and employed in the preparation of pentacyclic steroids by Granja, using a bicyclic diene generated by dienyne ringclosing metathesis. 43 Scheme 17 de Meijere's 2008 approach to the steroid skeleton Jung and Lui reported a third type of DA approach to the B-ring in their 2010 synthetic study towards the cucurbitacins 44 (Scheme 18), involving a semicyclic diene located on the A-ring fragment, with the CD-ring fragment containing the dienophile. Diene 75 was prepared in only three steps from a known diketone, 45 while dienophile 76 required a more lengthy 15-step synthesis.…”

Section: Scheme 12mentioning

confidence: 99%

The Diels–Alder Reaction in Steroid Synthesis

Mackay

Sherburn

2014

Synthesis

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This review explores the myriad ways in which the Diels-Alder reaction has been employed in the construction of the tetracyclic steroid nucleus. A systematic analysis of possible approaches highlights both the synthetic versatility of this ubiquitous reaction and also opportunities for new routes to fused tetracarbocyclic steroid frameworks. 1.1 Introduction 1.2 Classification of the Approaches 2.1 Installation of a Non-Skeletal Ring 2.2 Construction of the A-Ring 2.3 Construction of the BRing 2.4 Construction of the C-Ring 2.5 Double Diels-Alder Sequences 3 Conclusions and Future Prospects

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Section: Scheme 12mentioning

confidence: 99%

The Diels–Alder Reaction in Steroid Synthesis

Mackay

Sherburn

2014

Synthesis

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“…In particular, it has been utilized in a range of cycloaddition reactions. Interestingly, 1 has played both roles in 4+2 cycloadditions, as a doubly-activated dienophile 1 and as a heterodiene. 2 In earlier work, Meyer and coworkers attempted to conduct a Michael Addition to 1 , by reacting it with a β-ketoesterenolate in an effort to achieve a subsequent annulation reaction.…”

Section: Introductionmentioning

confidence: 99%

Improved synthesis of and nucleophilic addition to 2-formyl-2-cyclohexenone

Adary

Chang

Auria

et al. 2015

Tetrahedron Letters

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A preparation of 2-formyl-2-cyclohexenone in nearly quantitative yield and purity of approximately 95% is described. It is scalable and has been extended to the synthesis of the 5- and 7-membered ring homologs with comparable yields. Conditions have also been developed for the successful conjugate addition of dimethylmalonate to 2-formyl-2-cyclohexenone, in good and scalable yield (60%). This result has been extended to 5 other nucleophile classes, and the dimethylmalonate conjugate addition has been demonstrated with 2-formyl-2-cyclopentenone and 2-formyl-2-cycloheptenone.

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“…4 Only one account detailing a partial synthesis toward any family member has been presented to date. 5 The dense functionality and multiple adjacent stereocenters presented in the C and D rings of the cucurbitacins pose a significant synthetic challenge. The structure of cucurbitacin I with the hydrindane highlighted is shown in Figure 1.…”

mentioning

confidence: 99%