Butynyl iodide

Sunlamp irradiation of butynyl iodide (6) in the presence of hexabutylditin generates an alkyl radical that reacts with an electron-deficient alkene (7) to form an (iodomethylene)cyclopentene (8) in moderate yield. This product can be reduced by Bu3SnH (AIBN) to the methylenecyclopentane (9).2... 

Asymmetric atom-transfer annelations can also be effected. Thus irradiation of butynyl iodide with the acryloyl sultam 3 in the presence of Bu3SnSnBu3 at 80° followed by deiodination provides 5 as the major product. 

The yield of cyclized product for coupling between simple activated alkenes and butynyl iodides depends on the reduction potential of the Ni catalyst [200], since the radical resulting from the initial attack of the butynyl radical may either be reduced or cyclize (5—c.vo) on to the triple bond [Eq. (35)]. The lower the reduction potential of the catalyst, the more noncyclized product is formed. The yield of the cyclized product was in the range 30-60% [200]. 

Bicyclic pentenes are used as trapping agents in addition reactions of 3-butynyl radicals81. Addition occurs exclusively trans to the annulated cyclopentyl ring, while the regioselectivity is low when polar substituents are not present. Under thermal conditions, the reaction finishes after iodine atom abstraction to yield the overall trans-addition product. With photochemical initiation and in the presence of hexabutylditin, further cyclization and iodine atom abstraction occurs to form exocyclic vinyl iodides. 

Hydroxyquinoline-2-one with 3-chioro-3-methylbutyne refluxed in acetone containing potassium iodide and carbonate during 20 hours gave the butynyl ether, cyclisation of which in hot dimethylaniline at 200X for 2 hours furnished 3,3-dimethyl-3H-pyrano[3,2-f]quinoline-8(7H)-one (ref. 153). 

Methyl-3-hydroxy-l-butynyl)phenyl]-5-(3-methyl-3-hydroxy-l-butynyl)benzothiazole. A mixture consisting of 2-(3-bromophenyl)-5-bromobenzothiazole (24g, 65 mmole), dichlorobis(triphenylphosphine)-palladium II (.09g), triphenylphosphine (0.7g), cuprous iodide (0.26g) and triethylamine 250mL was heated to reflux and cooled to room temperature under a nitrogen atmosphere. To the mixture was added 2-methyl-3-butyn-2-ol ( 8g, 0.33 mole), heated to 90 C and maintained at that temperature for 24 h. The cooled reaction mixture was then filtered through a Celite pad to remove the amine hydrobromide and the triethylamine was removed under reduced pressure. The resultant brown solid was dissolved in chloroform, washed several times with sulfuric acid (10%), water and dried over anhydrous magnesium sulfate. Removal of the chloroform gave 23g (94%) of the product which was used without further purification. 

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