Cascade Metathesis Reactions for the Synthesis of Taxane and Isotaxane Derivatives
作者:Cong Ma、Aurélien Letort、Rémi Aouzal、Antonia Wilkes、Gourhari Maiti、Louis J. Farrugia、Louis Ricard、Joëlle Prunet
DOI:10.1002/chem.201600592
日期:2016.5.10
Tricyclic isotaxane and taxane derivatives have been synthesized by a very efficient cascade ring-closing dienyne metathesis (RCDEYM) reaction, which formed the A and B rings in one operation. When the alkyne is present at C13 (with no neighboring gem-dimethyl group), the RCEDYM reaction leads to 14,15-isotaxanes 16 a,b and 18 b with the gem-dimethyl group on the A ring. If the alkyne is at the C11
ZrCp2(isoprene) reacts with aliphatic aldehydes, ketones or nitriles regioselectively on C1-carbon of the isoprene moiety to give novel 2-oxa- or 2-aza-metallacycles which release alcohols or ketones respectively on hydrolysis. In contrast, ZrCH3(η1-methylallyl)Cp2, Ti(η3-methylallyl)Cp2, and [MgCH2C(CH3)=CHCH2]n reacted with acetone on the C3-carbon of the methylallyl or the isoprene unit.
Gallium-mediated allyl transfer from bulky homoallyl alcohol to aldehydes or alkynes: Control of dynamic σ-allylgalliums based on retro-allylation reaction
reagent and gallium trichloride, bulky homoallylalcohols undergo gallium-mediated retro-allylation reaction to provide σ-allylgallium reagents. The σ-allylgallium reagents generated were applied to carbonyl allylation. The retro-allylation reaction generates (Z)- and (E)-σ-crotylgalliums stereospecifically, starting from erythro- and threo-homoallyl alcohols, respectively. The stereochemically defined
Regioselectivity in electrochemical additions of the allyl groups in substituted allyl halides to α,β-unsaturated esters or acetone
作者:Shohei Satoh、Hiroshi Suginome、Masao Tokuda
DOI:10.1016/s0040-4039(01)90471-x
日期:1981.1
Electrochemical additions of the allyl groups in substituted allyl halides to some α,β-unsaturated esters took place in a regioselective manner at either of their α-or γ-carbon terminus, whereas regioselectivity in the addition to acetone was found to be controlled by changing a cathode material or an electrolytic potential.
Gallium-Mediated Allyl Transfer from Bulky Homoallylic Alcohol to Aldehydes via Retro-allylation: Stereoselective Synthesis of Both <i>e</i><i>rythro</i>- and <i>t</i><i>hreo</i>-Homoallylic Alcohols<sup>1</sup>
Retro-allylation of bulky gallium homoallylic alkoxides occurs to generate (Z)- and (E)-crotylgallium reagents stereospecifically, starting from erythro- and threo-homoallylic alcohols, respectively. The (Z)- and (E)-crotylgallium reagents immediately reacted with aromatic aldehydes to afford the corresponding erythro- and threo-homoallylic alcohols, respectively. [reaction: see text]