Methane, dichloromethoxy- → HCID 20728560, compound

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Reaction Steps

Compounds of the invention where the variable Y is an ethynyl-methyl (CH≡C—CH2—) group can, generally speaking, be synthesized in accordance with Reaction Scheme 12. The starting compound in accordance with this scheme is a 6-chromanoic acid ethyl ester derivative of Formula 3 which can be obtained as described above in connection with Reaction Scheme 1. The 6-chromanoic acid ethyl ester of Formula 3 is thereafter treated with α,α-dichloromethyl methyl ether in a suitable aprotic solvent such as methylene chloride to provide the 8-formyl-6-chromanoic acid ethyl ester derivative of Formula 12. The formyl compound of Formula 12 is reduced with sodium borohydride in methanol to give the corresponding hydroxymethyl compound of Formula 13. The hydroxymethyl compound of Formula 13 is then reacted with N-bromosuccinimide in the presence of triphenylphosphine in an aprotic solvent such as methylene chloride to give the 8-(bromomethyl)-6-chromanoic ester derivative of Formula 14. The 8-(bromomethyl)-6-chromanoic ester derivative of Formula 14 is reacted with trimethylsilyl acetylene in triethyl amine and dimethylformamide (DMF) under argon atmosphere in the presence of dichlorobis(triphenylphosphine)palladium(II) (Pd(PPh3)2Cl2). The trimethylsilyl group and the ethyl group of the ester moiety of the resulting 8-(trimethylsilylmethyl) 6-chromanoic acid ethyl ester are then removed by treatment with base (such as lithium hydroxide shown in the reaction scheme) to provide the 8-(ethynylmethyl)-6-chromanoic acid of Formula 15.

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