1) iodoalkynes from aldehydes

SyntheticPage 24
Published Jul 03, 2001

Reaction Scheme

Procedure

To iodoform stirring in THF is added triphenylphosphine and 1 equivalent of potassiumtbutoxide and the brown mixture is stirred for 1 minute. Cinnamaldehyde is added and the reaction stirred for 15 minutes, then cooled to -78C. The remaining potassiumtbutoxide is then added and the reaction stirred until completion (TLC immediately after the second addition of potassiumtbutoxide in order to ascertain which spot is the intermediate) then quenched with brine, extracted twice with ether, dried over magnesium sulphate, filtered, concentrated and purified by colummn chromatography eluting with 10% Et2O/PE.

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2) Triflic Acid Catalyzed Cyclization of trans-Cinnamaldehyde to 3-phenyl-1H-indene

SyntheticPage 764
Published Sep 15, 2014

Reaction Scheme

Procedure

To a well-stirred mixture of trans-cinnamaldehyde (15 g, 1 mol.) in benzene (150 mL) at about 0 oC to -5 oC was added Triflic acid (2 ml, 0.2 mol.) in portions. After the addition of the reagent, the cooling bath was removed. The reaction mixture was stirred at 60 oC for 15 h. The resultant reaction mixture was cooled at 0 oC and quench with triethyl amine (approx 5-7 ml) followed by ice cold water and extracted with ethyl acetate (200 mL×2). The combined organic layer dried over sodium sulphate and concentrated under reduced pressure. The residue was flash chromatographed (the eluent was pet ether) to give 20 g (92 %) of 3-phenylindene.

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