Synthesis of cannabinoids

1. A process for the preparation of a compound of formula (I-a),

the process comprising the steps of:

(a) converting a compound of formula (II-a) to a compound of formula (III-a), and

(b) converting the compound of formula (III-a) to the compound of formula (I-a),

wherein

R 1 and R 5 at each occurrence are independently hydroxyl or a protected hydroxyl group;

R 2 and R 4 at each occurrence are independently hydrogen or C 1 -C 10 alkyl;

R 3 at each occurrence is independently C 1 -C 10 alkyl;

R 6 and R 7 at each occurrence are independently hydrogen or C 1 -C 10 alkyl;

R 8 at each occurrence is independently hydroxyl, C 1 -C 10 alkyl, or C 1 -C 10 alkoxy;

wherein R 2 , R 3 , R 4 , R 6 , R 7 , and R 8 at each occurrence are independently optionally substituted with one or more substituents selected from the group consisting of alkenyl, alkynyl, alkoxycarbonyl, alkylcarbonyl, halogen, cyano, carboxyl, hydroxyl, protected hydroxyl, amino, oxo, aryl, arylcarbonyl, cycloalkyl, heteroaryl, and heterocycle; and

wherein step (b) is performed in a solvent selected from the group consisting of tetrahydrofuran and toluene.

2. The process of claim 1 , further comprising the step of reacting a compound of formula (IV-a) with a compound of formula (V) to produce the compound of formula (II-a)

3. The process of claim 2 , further comprising the step of converting a compound of formula (VI) to the compound of formula (IV-a)

4. The process of claim 3 , further comprising the steps of converting the compound of formula (VI) to a compound of formula (IV′), and reducing the compound of formula (IV′) to the compound of formula (IV-a)

5. The process of claim 1 , wherein step (a) comprises mixing potassium bis(trimethylsilyl)amide (KHMDS) with the compound of formula (II-a).

6. The process of claim 1 , wherein R 3 is —(CH 2 ) 4 —CH 3 .

7. The process of claim 1 , wherein R 1 and R 5 are —OCH 3 .

8. The process of claim 1 , wherein R 6 and R 7 are each —CH 3 .

9. The process of claim 1 , wherein R 8 is hydroxyl, —CH 3 , or —OCH 3 .

10. The process of claim 1 , wherein step (b) comprises mixing the compound of formula (III-a) with (1,3-Bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene)dichloro(phenylmethylene)(tricyclohexylphosphine)ruthenium.

11. A process for the preparation of a compound of formula (I), a racemate or a stereoisomer thereof,

the process comprising the steps of:

(a) converting a compound of formula (II) to a compound of formula (III), and

(b) converting the compound of formula (III) to the compound of formula (I),

further comprising the step of reacting a compound of formula (IV) with a compound of formula (V) to produce the compound of formula (II)

further comprising the steps of converting a compound of formula (VI) to a compound of formula (IV′), and reducing the compound of formula (IV′) to the compound of formula (IV)

wherein

R 1 and R 5 at each occurrence are independently hydroxyl or a protected hydroxyl group;

R 2 and R 4 at each occurrence are independently hydrogen or C 1 -C 10 alkyl;

R 3 at each occurrence is independently C 1 -C 10 alkyl;

R 6 and R 7 at each occurrence are independently hydrogen or C 1 -C 10 alkyl;

R 8 at each occurrence is independently hydroxyl, C 1 -C 10 , alkyl, or C 1 -C 10 , alkoxy;

wherein R 2 , R 3 , R 4 , R 6 , R 7 , and R 8 at each occurrence are independently optionally substituted with one or more substituents selected from the group consisting of alkenyl, alkynyl, alkoxycarbonyl, alkylcarbonyl, halogen, cyano, carboxyl, hydroxyl, protected hydroxyl, amino, oxo, aryl, arylcarbonyl, cycloalkyl, heteroaryl, and heterocycle.

12. A process for the preparation of a compound of formula (I), a racemate or a stereoisomer thereof,

the process comprising the steps of:

(a) converting a compound of formula (II) to a compound of formula (III), and

(b) converting the compound of formula (III) to the compound of formula (I),

wherein

R 1 and R 5 at each occurrence are independently hydroxyl or a protected hydroxyl group;

R 2 and R 4 at each occurrence are independently hydrogen or C 1 -C 10 alkyl;

R 3 at each occurrence is independently C 1 -C 10 alkyl;

R 6 and R 7 at each occurrence are independently hydrogen or C 1 -C 10 alkyl;

R 8 at each occurrence is independently hydroxyl, C 1 -C 10 alkyl, or C 1 -C 10 alkoxy;

wherein R 2 , R 3 , R 4 , R 6 , R 7 , and R 8 at each occurrence are independently optionally substituted with one or more substituents selected from the group consisting of alkenyl, alkynyl, alkoxycarbonyl, alkylcarbonyl, halogen, cyano, carboxyl, hydroxyl, protected hydroxyl, amino, oxo, aryl, arylcarbonyl, cycloalkyl, heteroaryl, and heterocycle;

wherein step (a) comprises mixing potassium bis(trimethylsilyl)amide (KHMDS) with the compound of formula (II).