New Routes to Isomerically Pure Cyclopentanes. Synthesis of (3<i>S</i>,4<i>S</i>)-3,4-Bis(benzoyloxymethyl)cyclopentan-1-ol using Palladium-Catalyzed [2 + 3] Cycloaddition

Janson, Marianne; Kvarnström, Ingemar; Svensson, Susanne; Classon, Björn; Samuelsson, Bertil

doi:10.1055/s-1993-25815

Cited by 10 publications

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“…Synthesis of the 1,5-hexadiyne-3,4-diol derivative 3 began with the known propargylic ketone 13 , available in two steps from ( S )-glyceraldehyde acetonide ( 12 ) (Scheme ). , In the course of synthetic studies of the neocarzinostatin chromophore, conditions had been developed for an E -selective Wittig reaction between 13 and the phosphonium salt 14 (KHMDS, THF, −78 °C, E : Z = 3:1) …”

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Enantioselective Synthesis of N1999A2

O'Dowd

Rosen

et al. 2006

J. Am. Chem. Soc.

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An enantioselective synthetic route to the enediyne antibiotic N1999A2 (1) is described, proceeding in 21 steps (0.4% yield, 77% average yield per step) from (R)-(+)-glycidol. The route involves the convergent assembly of three components: a (1-iodovinyl) stannane (2), a 1,5-hexadiyne-3,4-diol derivative (3), and a substituted naphthoic acid (4). Important transformations in the synthetic sequence include the palladium-catalyzed coupling of 2 and 3, an intramolecular oxidative cyclization of a terminal bisacetylene, and a transannular anionic (bi)cyclization of a cyclic bromoenetriyne. The careful selection and manipulation of protective groups throughout the sequence proved to be critical to the development of the synthetic route, where all late-stage intermediates were unstable and could not be concentrated. In the final step of the sequence, three protective groups were removed in a single operation, providing synthetic N1999A2 (1) in 76% yield. Conditions were found that, for the first time, led to the precipitation of 1 as a solid.

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confidence: 99%

Enantioselective Synthesis of N1999A2

O'Dowd

Rosen

et al. 2006

J. Am. Chem. Soc.

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“…17 Swern oxidation of (R)-2,3-O-isopropylideneglycerol 1 to (S)-2 and its further reaction, without isolation, has been reported. 18 However, our attempts to obtain pure 2 in good yield by Swern, Dess-Martin periodinane, Ley perruthenate, or TEMPO oxidation methods were unsuccessful. Finally, a practical route to 2 was found by oxidation of (R)-2,3-O-isopropylideneglycerol 1 with PCC.…”

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confidence: 98%