Synthesis of the Chiral CD Rings of Paclitaxel from 2-Deoxy-<scp>d</scp>-ribose:  Novel 1,2-Addition of a Dienolate to a Chiral Ketone

Takahashi, Takashi; Hirose, Yoichiro; Iwamoto, Hajime; Doi, Takayuki

doi:10.1021/jo9810563

Cited by 14 publications

(6 citation statements)

References 19 publications

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“…The nitrile oxide functional group is a well‐known 1,3‐dipole and highly useful owing to its high reactivity toward unsaturated C−C bonds to furnish [3+2] cycloadducts 1. In addition to such a traditional role, we have found that it also functions as an enophile2 in an intramolecular reaction with an allyltrimethylsilyl group 3. 5‐Methylene‐6‐(trimethylsilyl)hexanal oxime ( 1 a ) was treated with sodium hypochlorite4 in dichloromethane at 0 °C for 2 h to give the product of an ene‐like reaction ( 2 a ) in 82 % yield as a single diastereomer; no [3+2] cycloadducts, fused or bridged, were detected (Scheme ).…”

Section: Methodsmentioning

confidence: 96%

Novel Ene-Like Cycloisomerization Reaction of Nitrile Oxides with a Tethered Allyltrimethylsilyl Group

et al. 2002

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The nitrile oxide functional group is a well-known 1,3dipole and highly useful owing to its high reactivity toward unsaturated CÀC bonds to furnish [32] cycloadducts. [1] In addition to such a traditional role, we have found that it also functions as an enophile [2] in an intramolecular reaction with an allyltrimethylsilyl group. [3] 5-Methylene-6-(trimethylsilyl)hexanal oxime (1 a) was treated with sodium hypochlorite [4] in dichloromethane at 0 8C for 2 h to give the product of an enelike reaction (2 a) in 82 % yield as a single diastereomer; no fused a-methylene-g-butyrolactam, we explored the cyclocarbonylation of d-allenyl imine 3 and examined the stereochemistry of the resulting products (Scheme 4). We observed only the cis-fused a-methylene-g-butyrolactam 4 as the sole product, which supports a [2 2 1] cycloaddition. The cis stereochemistry of 4 was clearly determined by NOE interactions in NOESY experiments (see Supporting Information).Scheme 4. The cyclocarbonylation of d-allenyl imine 3 gave cis-fused amethylene-g-butyrolactam 4 as the sole product.

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Section: Methodsmentioning

confidence: 96%

Novel Ene-Like Cycloisomerization Reaction of Nitrile Oxides with a Tethered Allyltrimethylsilyl Group

et al. 2002

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“…The synthesis of appropriately protected epoxides 6 and 7 (Scheme ) was started from the known 3,5-di- O -benzyl-2-deoxy- D -ribofuranose ( 11 ) and 2,3,5-tri- O -benzyl- D -ribofuranose ( 12 ), respectively, which in turn were prepared from their corresponding sugars by following the reported procedure in three steps . The lactols 11 and 12 were reacted with methylenetriphenylphosphorane to give the alkenes 13 (63%) and 14 (31%), respectively, and the resulting secondary hydroxyl group was transformed to O -silyl ethers 15 (91%) and 16 (98%) by using TBSOTf in the presence of 2,6-lutidine.…”

mentioning

confidence: 99%

Total Synthesis and Stereochemical Revision of Acortatarins A and B

et al. 2011

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A first total synthesis of acortatarins A, B, and an enantiomer of the proposed structure of acortatarin B is described by using readily available d-sugars. This convergent total synthesis revealed the revision of the absolute configuration of acortatarin A and structural revision of acortatarin B. The key steps involved are regioselective epoxide opening with deprotonated 2,5-disubstituted pyrrole and spiroketalization.

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“…For example, the total synthesis of Taxol and its derivatives has attracted much recent interest, and it has been reported that entry to the fully functionalised taxane CD ring can be achieved via an intramolecular carbohydrate derived aldonitrone cycloaddition reaction. 31 However, integration of cycloaddition reactions of the less reactive ketonitrones has proved more challenging. Synthetically important examples of both strategies are provided below.…”

Section: Intramolecular Reactionsmentioning

confidence: 99%