Crystallization a 1alpha-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D3

1. 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 in crystalline form.

2. The crystalline form of 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 having molecular packing arrangement defined by space group P2 and unit cell dimensions a=6.6 Å b=15.8 Å c=20.0 Å α=90°, β=90° and γ=90°.

3. A three dimensional structure for 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 as defined by the molecular packing arrangement set forth in claim 2 .

4. A method of purifying 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 , comprising the steps of:

(a) preparing a solvent comprising ethyl formate;

(b) dissolving a product containing 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 to be purified in said solvent;

(c) cooling said solvent and dissolved product below ambient temperature for a sufficient amount of time to form a precipitate of 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 crystals; and

(d) separating the 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitaminD 3 crystals from the solvent.

5. The method of claim 4 including the further step of allowing said solvent and dissolved product to cool to ambient temperature prior to cooling below ambient temperature.

6. The method of claim 4 wherein said solvent comprises 100% ethyl formate, by volume.

7. The method of claim 4 wherein the step of separating comprises filtering the solvent and precipitate to obtain the crystals.

8. The method of claim 4 including a further step (e) comprising repeating steps (a) through (d) using the recovered crystals from step (d) as the product of step (b).

9. The method of claim 4 wherein said solvent comprises a mixture of ethyl formate and hexane.

10. The method of claim 9 wherein said mixture comprises about 75% ethyl formate and about 25% hexane, by volume.

11. A method of purifying 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 , comprising the steps of:

(a) preparing a solvent comprising ethyl formate;

(b) dissolving a product containing 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 to be purified in said solvent;

(c) cooling said solvent and dissolved product below ambient temperature for a sufficient amount of time to form a precipitate of 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 crystals; and

(d) recovering the 1α-hydroxy-20-methyl-2-methylene-19,24,25,26,27-pentanorvitamin D 3 crystals having a molecular packing arrangement defined by space group P2 and unit cell dimensions a=6.6 Å, b=15.8 Å, c=20.0 Å, α-90°, β=90° and γ=90°, or any other space group that yields substantially the same crystalline packing arrangement.

12. The method of claim 11 wherein said solvent and dissolved product is allowed to cool to ambient temperature prior to cooling below ambient temperature.

13. The method of claim 11 wherein said solvent comprises a mixture of ethyl formate and hexane.

14. The method of claim 13 wherein said mixture comprises about 75% ethyl formate and about 25% hexane, by volume.

15. The method of claim 11 wherein the step of recovering comprises filtering the solvent and precipitate to obtain the crystals.

16. The method of claim 11 including a further step (e) comprising repeating steps (a) through (d) using the recovered crystals from step (d) as the product of step (b).