Reactions of some alkynyl halides with Samarium(II) iodide

Allylstannylation of Carbon−Carbon and Carbon−Oxygen Unsaturated Bonds via a Radical Chain Process1

“…1-Methyl-2-propynyl acetate ( 24e ) was obtained from 3-butyn-2-ol by acetylation with AcCl−Et 3 N in Et 2 O . The reaction of methyl chloroformate with lithium acetylide derived from 1-hexyne was carried out for the synthesis of methyl 2-heptynoate ( 24f ) . Other substrates were purchased.…”

SmI2‐Induced Umpolung of the CN Bond: First Reductive Conjugate Addition of Nitrones to α,β‐Unsaturated Esters

“…While intramolecular SmI 2 ‐induced conjugate additions to α,β‐acetylenic esters have been reported to be sluggish20 and have allowed only the elaboration of five‐membered rings,21 no examples of the intermolecular version of these additions have been disclosed. It is noteworthy that the conjugate addition of nitrone‐derived α‐aza‐nucleophilic species to propiolates in presence of water proceeded smoothly (Table 1, entries 13, 14) to produce the corresponding γ‐ N ‐hydroxyamino‐α,β‐ethylenic esters as single isomers (100 % E ).…”

Recent developments in lanthanide mediated organic synthesis

“…The involvement of vinyl radicals generated by the addition of a samarium radical has been demonstrated in the cyclisation of ω-iodoalkynes 212 and the glycosyl sulfones discussed above, Scheme 20. 166 Such species undergo efficient cyclisation only if the concentration of the initial radical is sufficiently high; e.g.…”