Barbier coupling in water: SnCl2-mediated and Co(acac)2-catalyzed allylation of carbonyls

Making and Breaking of Sn−C and In−C Bonds in Situ: The Cases of Allyltins and Allylindiums

“…Allyl iodide can also be generated in situ from allyl alcohol using TMSCl/NaI; the corresponding carbonyl allylation leads to α-homoallylic alcohol (entry 2) . As mentioned earlier (vide Figure ), aqueous tin(II) chloride (2−5 M) mediates facile carbonyl allylation of aldehyde using allyl bromide (entry 3) . Ultrasonication also facilitates the reaction (entry 4) .…”

“…It is now well-accepted that a Tm−Sn II combination can efficiently mediate the Barbier allylation reaction in fully aqueous or aqueous−organic biphasic media. , These reactions are popularly included under the green-Barbier regime. Catalytic PdCl 2 [PPh 2 ( m -C 6 H 4 SO 3 Na)] 2 is efficient for the allylation of aldehydes in an aqueous−organic biphasic system (Scheme ) .…”

“…From this, one may conclude that allyltrihalostannane can be potentially employed in many nucleophilic addition reactions, including carbonyl allylation in an absolutely anhydrous medium. However, in most of the carbonyl allylation reactions presented so far in this section, − ,, an aqueous or aqueous−organic medium has been used. The influence of water has been often attributed to the generation of a more nucleophilic allyltin species such as [allyl-Sn(OH) n X 3− n ] or [allyl-Sn(H 2 O) m X n ] (3− n )+ .…”

Reactivity and Selectivity of Organotin Reagents in Allylation and Arylation: Nucleophilicity Parameter as a Guide

“…A number of studies have confirmed that Barbier allylation with organotin is facilitated by water. , However, the exact nature of the allyltin(IV) intermediates is often debated. Tagliavini and co-workers suggested the formation of either allylhydroxystannane or cationic hydrated allyltin intermediates .…”

Reactions of Aldehydes and Ketones and their Derivatives

“…193 Barbier coupling of aldehydes can be carried out in water using tin(II) chloride, with cobalt(II) acetylacetonate as catalyst. 194 In a gallium-mediated allyl transfer process, bulky gallium homoallylic alkoxides have been retro-allylated to generate (Z)-and (E)-crotylgallium reagents stereode specifically. 195 Immediate reaction with aromatic aldehydes gives erythro-and threohomoallylic alcohols.…”