Highly stereoselective syntheses of conjugated  , - and  , -dienes,  -enynes and  -1,2,3-butatriened via alkenylborane derivatives

Negishi, Ei‐ichi; Yoshida, Takao; Abramovitch, Akiva; Lew, George; Williams, Robert M.

doi:10.1016/s0040-4020(01)90494-6

Cited by 50 publications

(12 citation statements)

References 21 publications

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“…[3]Cumulenes are important substances, since they have potential applications in antitumor drug design and as advanced materials, as well as in organic synthesis . However, the stereoselective synthesis of cumulenes with reasonable generality is still rare . Our method provides an efficient and one-pot procedure for the stereoselective synthesis of cumulenes with multiple functionalities.…”

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confidence: 53%

Highly Efficient Synthesis of cis-[3]Cumulenic Diols via Zirconocene-Mediated Coupling of 1,3-Butadiynes with Aldehydes

Fan

et al. 2012

Organometallics

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A highly efficient and convenient method for the monozirconation of silyl- or tert-butyl-substituted 1,3-butadiynes using the Negishi reagent has been developed. The resulting zirconium butadiyne complexes undergo two syn-SE2′ reactions with various aldehydes to yield the cis-[3]cumulenic diols with moderate to high diastereoselectivities. The silyl substituents at the butadiyne terminus show remarkable influence on the diastereoselectivity.

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confidence: 53%

Highly Efficient Synthesis of cis-[3]Cumulenic Diols via Zirconocene-Mediated Coupling of 1,3-Butadiynes with Aldehydes

Fan

et al. 2012

Organometallics

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“…The absolute configuration of 10 was determined through its conversion into the known compound (+)‐(1 R )‐3‐oxo‐1‐phenyl‐1‐butanol 11 by ozonolysis. The E configuration of the [3]cumulene was assigned on the basis of our mechanistic model for the processes involved, that is, pre‐transition‐state structure B 11a,b…”

Section: Methodsmentioning

confidence: 99%

OC195: The transvaginal ultrasound based acute gynaecology unit: Short term follow up of women seen with acute pelvic pain

Okaro

Condous

Khalid

et al. 2003

Ultrasound Obstet Gynecol

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Oral communication abstracts and end systolic volumes were measured, and ejection fraction was calculated for each ventricle. Results: In approximately 90% of cases in which the fourchamber view was visualized, it was possible to calculate ventricular volumes. Volume of both ventricles increased in the course of pregnancy correlating with gestational age and estimated fetal weight. Unexpectedly, there was no significant difference between right and left ventricular volumes in the gestational ages studied. Ejection fraction of the ventricles was calculated at about 70%. Conclusion: 3D echocardiography can provide estimates of ventricular volume and function and may be used for evaluation of fetuses with congenital heart disease. OC189 4D-STIC (spatio-temporal image correlation) fetal echocardiography: a new tool for prenatal screening of cardiac defects

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“…Substrates . 2-[[(Trifluoromethyl)sulfonyl]oxy]-1-octene, 2-[[(trifluoromethyl)sulfonyl]oxy]-1-hexene, 1-iodo-1-hexyne, ( Z )-crotyl bromide ( Z - 23 ), and methyl 7-oxoheptanoate were prepared according to the literature procedures cited. 2-Iodo-1-hexene was obtained upon reaction of 1-hexyne with 9-iodo-9-BBN, followed by deborylation with HOAc…”

Section: Methodsmentioning

confidence: 99%

Nozaki−Hiyama−Kishi Reactions Catalytic in Chromium

1996

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A procedure is described which allows for the first time to perform chromium-catalyzed additions of organic halides to aldehydes (“Nozaki−Hiyama−Kishi reactions”). The reactions are mediated by trimethylchlorosilane, and the active Cr²⁺ species is constantly recycled by means of nontoxic, commercial manganese powder as the stoichiometric reductant. This method nicely applies to different substituted aryl, heteroaryl, alkynyl, alkenyl, and allyl halides as well as to alkenyl triflates as the starting materials and rivals its stoichiometric precedent in terms of efficiency, practicability, and chemo- and diastereoselectivity. Specifically, it has been demonstrated that the addition of crotyl bromide to various aldehydes is highly stereoconvergent, i.e. the respective anti-configurated homoallyl alcohols are obtained with excellent diastereomeric excess independent of whether the starting halide is (E)- or (Z)-configurated. In accordance with the likely catalytic cycle, both CrCl₂(cat.) or CrCl₃(cat) turned out to efficiently mediate reactions of this type, with the latter being preferred for practical reasons. Finally, attempts were made to optimize the number of turnovers in chromium. In this context the use of either chromocene (Cp₂Cr) or CpCrCl₂·THF as “pre-catalysts” were found to significantly upgrade the efficiency of such C−C bond formations, with ≤1 mol % of chromium being required in these cases for quantitative conversions

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Highly stereoselective syntheses of conjugated , - and , -dienes, -enynes and -1,2,3-butatriened via alkenylborane derivatives

Cited by 50 publications

References 21 publications

Highly Efficient Synthesis of cis-[3]Cumulenic Diols via Zirconocene-Mediated Coupling of 1,3-Butadiynes with Aldehydes

Highly Efficient Synthesis of cis-[3]Cumulenic Diols via Zirconocene-Mediated Coupling of 1,3-Butadiynes with Aldehydes

OC195: The transvaginal ultrasound based acute gynaecology unit: Short term follow up of women seen with acute pelvic pain

Nozaki−Hiyama−Kishi Reactions Catalytic in Chromium

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