A New Recyclable Ditribromide Reagent for Efficient Bromination under Solvent Free Condition
摘要:
1,2-Dipyridiniumditribromide-ethane (DPTBE) has been synthesized and explored as a new efficient brominating agent. The crystalline ditribromide reagent is stable for months and acts as a safe source of bromine requiring just 0.5 equiv for complete bromination. It has high active bromine content per molecule and shows a remarkable reactivity compared to other tribromide reagents toward various substrates by just grinding the reagent and substrates in a porcelain mortar at room temperature. No organic solvent has been used during any stage of the reaction for substrates giving product as solid. Product can easily be isolated by just washing the highly water soluble 1,2-dipyridiniumdibromide-ethane (DPDBE) from the brominated product. The spent reagent can be recovered, regenerated, and reused without any significant loss.
In the title reaction, eight vic-dibromides and three vinylene dibromides gave the corresponding debromination products (alkenes and alkynes) at room temperature under neutral condition and an argon atmosphere. 2,3-Dibromosuccinic acid derivatives gave overreduction products or an unusual coupling dimer.
Nickel mediated double bond formation from vic-dibromides and ethyl magnesium bromide
作者:Corrado Malanga、Laura A. Aronica、Luciano Lardicci
DOI:10.1016/0040-4039(95)01988-t
日期:1995.12
vic-dibromides are quantitatively convened into alkenes by using a catalytic amount of NidppeCl2, in the presence of two molar equivalents of EtMgBr in THF. Stereochemical aspects of the reaction are given.
Gadolinium DOTA Chelates Featuring Alkyne Groups Directly Grafted on the Tetraaza Macrocyclic Ring: Synthesis, Relaxation Properties, “Click” Reaction, and High-Relaxivity Micelles
作者:Christian Vanasschen、Nouri Bouslimani、David Thonon、Jean F. Desreux
DOI:10.1021/ic2010997
日期:2011.9.19
reports on the synthesis and relaxivity properties of tetraacetic DOTA-type chelating agents featuring one or two alkyne groups directly grafted on the tetraaza macrocyclic ring and available for “click” reactions with azide-bearing substrates. The racemic DOTAma ligand bearing one alkyne group was obtained by a bisaminal template route. The same approach was used to prepare ligand DOTAda substituted