Intermediates useful for the synthesis of huperzine A

A compound represented by the formula:

• wherein:
• R1 is lower alkyl, benzyl, or substituted benzyl;
• X is a suitable leaving group;
• Y is selected from the group consisting of hydrogen, —NO2, —NR3R4, —CH═NOR5, —COR6, —CO2R6, —C(O)NR6R7, —CN, —C(S)NR6R7, —N3, and —N═CR8R9;
• R3 and R4 are independently selected from the group consisting of —C(O)OR10, —C(O)R10, phenacyl, and 3-acetoxypropyl or R3 and R4 may be taken together to form a cyclic imide;
• R5 is selected from the group consisting of hydrogen, lower alkyl, and aryl;
• R6 and R7 are independently selected from the group consisting of hydrogen, lower alkyl, substituted lower alkyl, aryl, and substituted aryl or R6 and R7 may be taken together to form a heterocyclic ring;
• R8 and R9 are independently selected from the group consisting of hydrogen, lower alkyl, substituted lower alkyl, aryl, and substituted aryl or R8 and R9 may be taken together to form a ring;
• and
• R10 is selected from the group consisting of lower alkyl, substituted lower alkyl, aryl, substituted aryl, adamantyl, cinnamyl, 2-trimethylsilylethyl, 2-phenylethyl, vinyl, allyl, benzyl, and substituted benzyl.

A method of synthesizing a compound of a formula 3:

• comprising contacting a compound of a formula:
• with a compound of a formula:
• in the presence of a suitable base, to make the compound of formula 3, wherein:
• R1 is lower alkyl, benzyl, or substituted benzyl;
• Y is selected from the group consisting of —NO2, —NR3R4, —CH═NOR5, —COR6, —CO2R6, —C(O)NR6R7, —CN, —C(S)NR6R7, —N3, and —N═CR8R9;
• R3 and R4 are independently selected from the group consisting of —C(O)OR10, —C(O)R10, phenacyl, and 3-acetoxypropyl or R3 and R4 may be taken together to form a cyclic imide;
• R5 is selected from the group consisting of hydrogen, alkyl, and aryl;
• R6 and R7 are independently selected from the group consisting of hydrogen, alkyl, and aryl or R6 and R7 may be taken together to form a heterocyclic ring;
• R8 and R9 are independently selected from the group consisting of hydrogen, alkyl, and aryl or R8 and R9 may be taken together to form a ring;
• R10 is selected from the group consisting of alkyl, aryl, adamantyl, cinnamyl, 2-trimethylsilylethyl, 2-phenylethyl, vinyl, allyl, and benzyl;
• and
• X and L are independently selected from the group consisting of iodo, bromo, chloro, alkylsulfonyloxy, arylsulfonylox, and phenoxy.

A method of synthesizing a compound of a formula 2:

• comprising contacting a compound of a formula:
• with a compound of a formula:
• in the presence of a base, to make the compound of formula 2, wherein:
• R1 is lower alkyl, benzyl, or substituted benzyl;
• Y is selected from the group consisting of —NO2, —NR3R4, —CH═NOR5, —COR6, —CO2R6, —C(O)NR6R7, —CN, —C(S)NR6R7, —N3, and —N=CR8R9;
• R3 and R4 are independently selected from the group consisting of —C(O)OR10, —C(O)R10, phenacyl, and 3-acetoxypropyl or R3 and R4 may be taken together to form a cyclic imide;
• R5 is selected from the group consisting of hydrogen, alkyl, and aryl;
• R6 and R7 are independently selected from the group consisting of hydrogen, alkyl, and aryl or R6 and R7 may be taken together to form a heterocyclic ring;
• R8 and R9 are independently selected from the group consisting of hydrogen, alkyl, and aryl or R8 and R9 may be taken together to form a ring;
• R10 is selected from the group consisting of alkyl, aryl, adamantyl, cinnamyl, 2-trimethylsilylethyl, 2-phenylethyl, vinyl, allyl, and benzyl;
• X and L are independently selected from the group consisting of iodo, bromo, chloro, alkylsulfonyloxy, arylsulfonylox, and phenoxy;
• and
• one broken line is present as a carbon—carbon bond and the other broken line is absent, where the broken line completes an unconjugated carbon—carbon double bond, which double bond is endocyclic whereby n is 3 or the double bond is exocyclic whereby n is 2.