Synthesis of C16–C27-fragments of bryostatins modified by 20,20-difluorination

Mears, Paul R.; Thomas, Eric J.

doi:10.1016/j.tetlet.2015.05.007

Cited by 8 publications

(2 citation statements)

References 43 publications

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“…Such oxidations of fluorinated alcohols have been reported to be challenging, but have now been reported efficiently under several conditions. Dess–Martin oxidation has been reported to be the most reliable and general conditions for fluoroalkyl alcohol oxidation (Scheme ), but other conditions including Swern oxidation, Jones oxidation, PDC oxidation and TPAP/NMO oxidation have all been reported in high yield.…”

Section: Synthesis Of Difluoroketones By a Fluorinated‐building‐blmentioning

confidence: 99%

Methods for the Synthesis of α,α‐Difluoroketones

Pattison

2018

Eur J Org Chem

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α,α‐Difluoroketones are valuable compounds and can be used as synthetic intermediates for the synthesis of fluorinated molecules, but they also have a direct application in medicinal chemistry, particularly as inhibitors for hydrolytic enzymes. This Microreview will summarize the major methods currently available for the synthesis of α,α‐difluoroketones, highlighting methods involving direct C–F bond formation, as well as those using pre‐difluorinated building blocks.

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Section: Synthesis Of Difluoroketones By a Fluorinated‐building‐blmentioning

confidence: 99%

Methods for the Synthesis of α,α‐Difluoroketones

Pattison

2018

Eur J Org Chem

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“…To this end, studies were initiated directed towards the synthesis of bryostatin analogues with fluorine substituents at C20. 35 Further details of these studies will be described in the final paper in this series.…”

Section: Completion Of a Synthesis Of 7-des-o-pivaloyl-7-obenzylbryostatin 10mentioning

confidence: 99%

Total synthesis of 7-des-O-pivaloyl-7-O-benzylbryostatin 10

et al. 2017

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The first total synthesis of a derivative of a 20-deoxybryostatin, namely 7-des-O-pivaloyl-7-O-benzylbryostatin 10 is described. Preliminary studies demonstrated that the modified Julia reactions of 2-benzothiazolylsulfones corresponding to the C17-C27 fragment with aldehydes corresponding to the C1-C16 fragment, provided an efficient and stereoselective assembly of advanced intermediates with the (E)-16,17-double-bond. The synthesis of the C1-C16 fragment was then modified so that the C1 acid was present as its allyl ester before the Julia coupling. A more efficient synthesis of the C17-C27 sulfone was developed in which a key step was the bismuth mediated coupling of an allylic bromide with an aldehyde in the presence of an acrylate moiety in the allylic bromide. A scalable synthesis of an advanced macrolide was completed using the modified Julia reaction followed by selective deprotection and macrolactonisation. The final stages of the synthesis required selective hydroxyl deprotection and the introduction of the sensitive C19-C21 unsaturated keto-ester functionality. Unexpected selectivities were observed during studies of the hydroxyl group deprotections. In particular, cleavage of tri-isopropylsilyl ethers of the exocyclic primary allylic alcohols was observed in the presence of the triethylsilyl ether of the secondary alcohol at C19. Model studies helped in the design of the methods used to introduce the C19-C21 keto-ester functionality and led to the completion of a total synthesis of a close analogue of bryostatin 10 in which a benzyloxy group rather than the pivaloyloxy group was present at C7.

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A General Approach to Various Five‐ and Six‐Membered gem‐Difluoroheterocycles: Application to the Synthesis of Fluorinated Analogues of Sedamine

et al. 2018

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A new synthesis of a group of O‐, S‐ and N‐heterocycles with a gem‐difluoro group in position β to the heteroatom has been developed, starting from easily accessible gem‐difluoro propargylic derivatives. This tandem process involves a base‐induced isomerization followed by an intramolecular 1,4 hetero‐Michael addition. This methodology is suitable for the preparation of five‐ and six‐membered heterocycles and it has been successfully applied to the synthesis of the 3,3‐difluoro analogues of (±)‐sedamine III, (±)‐allosedamine V, (±)‐norallosedamine II, and (±)‐norsedamine IV.

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Synthesis of C16–C27-fragments of bryostatins modified by 20,20-difluorination

Cited by 8 publications

References 43 publications

Methods for the Synthesis of α,α‐Difluoroketones

Methods for the Synthesis of α,α‐Difluoroketones

Total synthesis of 7-des-O-pivaloyl-7-O-benzylbryostatin 10

A General Approach to Various Five‐ and Six‐Membered gem‐Difluoroheterocycles: Application to the Synthesis of Fluorinated Analogues of Sedamine

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