(1R,3R)-2-Methylene-1,3-dithiolane 1,3-dioxide: A highly reactive and selective chiral ketene equivalent.

Aggarwal, Varinder K.; Drabowicz, J.; Grainger, Richard S.; Gültekin, Zeynep; Lightowler, Mark; Spargo, Peter L.

doi:10.1021/jo00121a002

Cited by 67 publications

(56 citation statements)

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“…Higher selectivity was obtained with phenylthio-rather than methylthioacrylates (entries 1, 3), and higher selectivity was also obtained with small or moderately sized ester substituents [Me, Et, iPr ϾϾ tBu (entries 2, 3,6,8,9)]. The tBu ester was much less reactive than the other esters and the reaction had to be conducted at 0°C (entry 8).…”

Section: Resultsmentioning

confidence: 99%

“…[5Ϫ7] We have been interested in developing ketene equivalents for DielsϪAlder reactions and have therefore sought dienophiles that could be easily converted into carbonyl compounds. Initially, we utilised bis-sulfoxides of ketene thioacetals as chiral ketene equivalents, [8] but this auxiliarybased approach is limited compared to catalytic methods. We therefore considered the possibility of using chiral Lewis acids with dienophiles in which the activating groups could be readily converted into a carbonyl functionality.…”

Section: Introductionmentioning

confidence: 99%

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Copper(II)-Bisoxazoline-Catalysed Asymmetric Diels−Alder Reactions of α-Thioacrylates

Aggarwal¹,

Jones²,

Martín-Castro³

2000

Eur. J. Org. Chem.

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A range of C 2 -symmetric, chiral Cu II ·bisoxazoline complexes were tested as catalysts for the asymmetric Diels−Alder cycloaddition between cyclopentadiene and a range of α-sulfenylacrylates. The optimum acrylate was ethyl α-phenylthioacrylate and the optimum catalyst was the bisoxazoline derived from phenylalanine which, upon complexation with Cu(SbF 6 ) 2 , gave the cycloadducts in 92% yield, 88% de and

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Copper(II)-Bisoxazoline-Catalysed Asymmetric Diels−Alder Reactions of α-Thioacrylates

Aggarwal¹,

Jones²,

Martín-Castro³

2000

Eur. J. Org. Chem.

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“…143 The idea was to synthesize a common intermediate or “priviledged intermediate” which could be elaborated into sarpagine alkaloids. Reaction of oxidopyridinium ion 234 with Aggarwal’s chiral ketene equivalent 235 144 in the presence of DIPEA in DCM afforded the cycloadduct 236 via a [5+2] cycloaddition reaction (Scheme 15). The cycloadduct 236 was obtained in a 2:1 ratio in favor of the desired regioisomer and 93% ee.…”

Section: Synthesismentioning

confidence: 99%

Sarpagine and Related Alkaloids

Namjoshi

Cook

2016

The Alkaloids: Chemistry and Biology

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The sarpagine-related macroline and ajmaline alkaloids share a common biosynthetic origin, and bear important structural similarities, as expected. These indole alkaloids are widely dispersed in 25 plant genera, principally in the Apocynaceae family. Very diverse and interesting biological properties have been reported for this group of natural products. Isolation of new sarpagine-related alkaloids as well as the asymmetric synthesis of these structurally complex molecules are of paramount importance to the synthetic and medicinal chemists. A total of 115 newly isolated sarpagine-related macroline and ajmaline alkaloids, along with their physicochemical properties have been included in this chapter. A general and efficient strategy for the synthesis of these monomeric alkaloids, as well as bisindoles has been presented, which involves application of the asymmetric Pictet–Spengler reaction (>98% ee) as a key step because of the ease of scale up of the tetracyclic template. Also included in this chapter are the syntheses of the sarpagine-related alkaloids, published since the year 2000.

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“…For oxidation of a wide range of 2-substituted 1,3-dithianes (44) according to Kagan's procedure see [95] and references therein. Aggarwal and co-workers extensively studied the mono-and bisoxidation of 1,3-dithianes and compared the Kagan and Modena systems [40,96]. The former one was good for monooxidation to 43, whereas the latter was found to be a good oxidizing system for the selective synthesis of the dioxide 45.…”

Section: Some Applications Of the Titanium Based Systemsmentioning

confidence: 99%