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A 1,6-Conjugate addition attacks the delta carbon of an extended conjugated electrophile. The resulting extended enolate can be protonated at different sites; proton transfer or equilibration can favor a product retaining carbonyl–alkene conjugation.

An alkenyl aluminate has an anionic aluminium-containing unit attached to an alkene carbon. Intramolecular oxygen coordination can close a five-membered ring in directed propargylic alcohol reductions.

A carbon fragment doubly bonded to a metal in the present organometallic usage. Metal–alkylidene exchange with an alkene underlies olefin metathesis.

Axial stereoisomerism in suitably substituted alkylidenecyclohexanes, where the constrained ring and alkene distinguish two handed arrangements.

The compound $\mathrm{C}{\mathrm{H}}_2=\mathrm{CHC}{\mathrm{H}}_2\mathrm{Br}$. nucleophilic substitution at its bromomethylene carbon introduces an allyl group without consuming the alkene.

An addition whose regiochemical outcome is opposite to the conventional Markovnikov orientation. hydroboration followed by oxidation places OH at the less substituted alkene carbon.

Beta-hydride elimination transfers hydrogen from the beta carbon of a metal-bound alkyl to the metal while forming an alkene. It can release a growing polymer chain and compete with migratory insertion. Its accessibility depends on geometry, available sites and bond energetics.

Addition of bromine and an oxygen nucleophile across an alkene to form a bromoether. Intramolecular attack on a bromonium ion can close a ring; tether length, charge distribution and anti opening determine the resulting connectivity.

A bromonium ion bridges both carbons of an alkene-derived three-membered ring. Bromide opening from the opposite face gives an anti vicinal dibromide and avoids a freely rotating open carbocation.

Reduction using hydrogen and a catalyst. Selectivity depends on the catalyst, pressure, solvent and functional groups: reducing an alkene while retaining a ketone is a distinct requirement from reducing a nitrile while retaining an ester.

A hydrosilylation cycle involving Si–H oxidative addition, alkene insertion into the metal–hydride bond, and C–Si reductive elimination. This defines the conventional version; insertion into a metal–silyl bond describes a modified alternative.

An ester containing the conjugated fragment Ph-CH=CH-C(=O)-O-R. Its trans alkene commonly has a large vicinal proton coupling, while HMBC can connect an alkoxy methylene to the ester carbonyl.

The Cossee-Arlman mechanism propagates a polymer through alkene coordination followed by insertion into a metal–carbon bond. Repetition extends the metal-bound chain. Regioselectivity controls monomer connectivity; it does not by itself specify tacticity.

A cyclic osmate ester contains the newly formed carbon–oxygen bonds of an osmium-mediated alkene dihydroxylation. Both oxygen atoms attach on the same face; hydrolytic cleavage of metal–oxygen bonds releases the diol.

A puckered conformation with an approximately planar alkene end and a nonplanar saturated part. Bulky substituents commonly favor pseudoequatorial positions.

The Dewar-Chatt-Duncanson model describes an alkene–metal bond through donation from the filled alkene $\pi$ orbital to the metal and pi backbonding from the metal into alkene ${\pi }^{\ast }$. Backbonding weakens and lengthens the alkene double bond. A $d^0$ early-metal ion has little conventional $d$-electron backbonding.

Dihydroxylation installs hydroxyl groups on adjacent alkene carbons. osmium tetroxide gives a syn addition pathway through a cyclic osmate ester.

An ether with oxygen directly attached to an alkene carbon. Electrophilic activation and hydrolysis can convert an appropriate enol ether back to a carbonyl compound.

Addition of an aldehydic C–H bond across an unsaturated bond, creating a ketone. Intramolecular alkene hydroacylation commonly constructs a five-membered ring via an acyl–metal hydride, alkene insertion and reductive elimination.

The monoanionic ${\mathrm{C}}_8{\mathrm{H}}_7^{-}$ coordination ligand obtained by removing one proton from dihydropentalene. An aromatic five-membered portion can bind a metal in an eta-five mode while the fused ring retains an uncoordinated alkene.