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Articles Archive for April 2006

Still In The RBF »

[26 Apr 2006 | 3 Comments | 5,162 views]

Crimmins, Zhang and Diaz. Org. Let., 2006, ASAP. DOI: 10.1021/ol060704z
Ruthenium-tastic total synthesis of the polyether Mucocin, using three metathesis reactions in this paper. Most interesting was the creation of the central THF as a 2,5-DHF via a Hoye-type activation strategy. This involves using a allyloxymethyl side chain to direct the Ru complex insertion, resulting in preferential formation of the 5-member ring.

Coupling of this fragment to the right-hand piece proceeded via a efficient Sonogashira coupling and subsequent diimide reduction, whilst the left-hand section was inserted via metathesis, in a similar fashion …

Still In The RBF »

[26 Apr 2006 | 6 Comments | 6,732 views]

Weinreb and Jeong. Org. Let., 2006, ASAP. DOI: 10.1021/ol060556c
Using some really smart 1,3-di-polar chemistry, Weinreb has completed a formal synthesis of Haouamine. Working towards the Baran indenotetrahydropyridine pentacyclic intermediate, they used a 1,3-DPC to put in the indene system very quickly, but isolated two products from the cyclisation. However, the undesired product was converted to the desired by simply heating, resulting in a 76% yield.

However, the ambitious RCM chemistry using a terminal vinyl chloride was less successful, and required a rethink to complete this work.

Still In The RBF »

[24 Apr 2006 | 8 Comments | 6,872 views]

Nicolaou and Harrison. ACIE, 2006, Early View. DOI: 10.1002/anie.200601116

An interesting approach to the abyssomicin family, this time of the C varient. Without getting into the DMDO-related debacle of the Sorensen and Snider papers (though the discrepency is worth a read!), this is an incredibly popular target. Unsurprising, I guess, due to it’s biological profile, but I’m sure we’ll see a few more syntheses before the year is out.

KC’s route uses an impressive DA to put in the six-member ring, generating two stereocentres, in a process somewhat similar to Ward’s. The …

Still In The RBF »

[21 Apr 2006 | 4 Comments | 7,055 views]

Trost and Dong. JACS., 2006, ASAP. DOI: 10.1021/ja061105q

A very rapid synthesis of Agelastatin A, using palladium chemistry (surpise) in two steps. However, both these steps go in remarkable yield, completing the 5-6-5 core of the target in four steps!

The remaining 5-member ring is constucted in an elegant two-step process; aziridination using a new-to-application N-heterocyclic carbene catalyst, followed by hydrolytic ring opening. Top stuff.

Still In The RBF »

[21 Apr 2006 | 2 Comments | 4,792 views]

Crimmins, and Slade. Org. Lett., 2006, ASAP. DOI: 10.1021/ol0607241
Formal synthesis of 6-Deoxyerythronolide B, using Crimmins aldol methodology (this blog’s turning into Aldol News) to put in eight of the nine stereocentres. Their method revolves around the iterative asymmetric acyl-thiazolidinethione propionate aldol:

Getting around 80% yield and >20:1 dr in each of these aldols makes this a pretty sweet job, if a little repetitive.

Still In The RBF »

[19 Apr 2006 | One Comment | 7,849 views]

Paterson, Findlay and Florence. Org. Lett., 2006, ASAP. DOI: 10.1021/ol060609q
Reassigning the structure of Dolastatin based upon his synthesis of callipeltoside, Paterson used two 1,4-syn boron aldols to configure a considerable section of Dolatstatin, finishing the total synthesis in a neat 23-step campaign. The sugar-unit was derived directly from L-rhamnose, appending in moderate yield, but with impressive stereochemical control.

Still In The RBF »

[1 Apr 2006 | 4 Comments | 5,034 views]

Phillips and O’Neil. JACS, 2006, ASAP. DOI: 10.1021/ja0609708
Showcasing their (silyloxy)enyne cyclisation (twice) in this neat synthesis, they used a SGHWE to complete the final macrocyclisation in 74%. However, it is their methodology that is most impressive:

Retrosynthetic »

[1 Apr 2006 | One Comment | 3,184 views]

Campagne, Parenty & Moreau. Chem. Rev., 2006, 106, 911-939. DOI: 10.1021/cr0301402
Excellent review of the use of macrolactonisations (apparently there’s more to it than Yamaguichi) in total syntheses, covering all the main methods, and showing their use in some pretty interesting products.