A method of preparing a crystalline form of a salt of a β-turn peptidomimetic cyclic compound of formula wherein: R 1 is hydrogen, C 1 to C 6 alkyl, aryl, or an amino acid side chain substituent of a natural or unnatural amino acid; R 3 is hydrogen, C 1 to C 6 alkyl, aryl, or an amino acid side chain substituent of a natural or unnatural amino acid; R 2 and R 4 are independently hydrogen or C 1 to C 6 alkyl, or R 1 and R 2 together with the carbon atom to which they are attached form a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group, or R 1 and R 2, R 3 and R 4 together with the carbon atom to which they are attached form a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group; Y is selected from the group consisting of hydrogen, -NO 2, - COOR 14, - OC(R 14) 3, -SO 3 R 14, and -SO 2 R 14; R 5, R 6, R 7 R 8, and R 9 are independently hydrogen or C 1 to C 6 alkyl; R 10 is hydrogen, methyl, t-butyl, or a protecting group; and each R 14 is hydrogen, alkyl or aryl; X is selected from the group consisting of O, NR 9, S, P, Se, C 1 to C 6 alkylene, SO, SO 2 and NH; n is 0, 1, 2, 3, 4 or 5; the method comprising steps of: (a) providing a protected linear peptidomimetic compound of formula wherein: R 2, R 4, R 5, R 6 R 7 R 8, R 10, X, Y, and n have the meanings defined above; R 11 and R 13 are independently hydrogen or a protecting group; R 12 is a protecting group; W 1 and W 3 are independently an amino acid side chain substituent of a natural or unnatural amino acid, less a hydrogen atom at the point of attachment to R 11 and R 13 respectively; and Z is selected from the group consisting of F, Cl, Br and I; (b) selectively deprotecting the compound of formula to form a partially protected linear peptidomimetic compound of formula wherein: R 2, R 4, R 5, R 6, R 7 R 8, R 10, R 11, R 13, W 1, W 3, X, Y, Z, n have the meanings defined above; (c) cyclizing the partially protected linear peptidomimetic compound of formula to form a compound of formula by an intramolecular aromatic nucleophilic substitution reaction wherein: R 2, R 4, R 5, R 6, R 7 R 8, R 10, R 11, R 13, W 1, W 3, X, Y, and n have the meanings defined above; (d) deprotecting an amino acid side chain protecting group in the compound of formula to obtain the salt of the β-turn peptidomimetic cyclic compound of formula; and (e) crystallizing the salt of the β-turn peptidomimetic cyclic compound of formula to obtain the compound of formula in crystalline form, wherein the crystallizing comprises contacting the compound or salt of formula with a basic solution having a basic pH, and reducing the pH to obtain an acidic pH to precipitate or crystallize the compound or salt of formula. R 1 is hydrogen, C 1 to C 6 alkyl, aryl, or an amino acid side chain substituent of a natural or unnatural amino acid; R 3 is hydrogen, C 1 to C 6 alkyl, aryl, or an amino acid side chain substituent of a natural or unnatural amino acid; R 2 and R 4 are independently hydrogen or C 1 to C 6 alkyl, or R 1 and R 2 together with the carbon atom to which they are attached form a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group, or R 1 and R 2, R 3 and R 4 together with the carbon atom to which they are attached form a cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl group; Y is selected from the group consisting of hydrogen, -NO 2, - COOR 14, - OC(R 14) 3, -SO 3 R 14, and -SO 2 R 14; R 5, R 6, R 7 R 8, and R 9 are independently hydrogen or C 1 to C 6 alkyl; R 10 is hydrogen, methyl, t-butyl, or a protecting group; and each R 14 is hydrogen, alkyl or aryl; X is selected from the group consisting of O, NR 9, S, P, Se, C 1 to C 6 alkylene, SO, SO 2 and NH; n is 0, 1, 2, 3, 4 or 5; (a) providing a protected linear peptidomimetic compound of formula wherein: R 2, R 4, R 5, R 6 R 7 R 8, R 10, X, Y, and n have the meanings defined above; R 11 and R 13 are independently hydrogen or a protecting group; R 12 is a protecting group; W 1 and W 3 are independently an amino acid side chain substituent of a natural or unnatural amino acid, less a hydrogen atom at the point of attachment to R 11 and R 13 respectively; and Z is selected from the group consisting of F, Cl, Br and I; R 2, R 4, R 5, R 6 R 7 R 8, R 10, X, Y, and n have the meanings defined above; R 11 and R 13 are independently hydrogen or a protecting group; R 12 is a protecting group; W 1 and W 3 are independently an amino acid side chain substituent of a natural or unnatural amino acid, less a hydrogen atom at the point of attachment to R 11 and R 13 respectively; and Z is selected from the group consisting of F, Cl, Br and I; (b) selectively deprotecting the compound of formula to form a partially protected linear peptidomimetic compound of formula wherein: R 2, R 4, R 5, R 6, R 7 R 8, R 10, R 11, R 13, W 1, W 3, X, Y, Z, n have the meanings defined above; (c) cyclizing the partially protected linear peptidomimetic compound of formula to form a compound of formula by an intramolecular aromatic nucleophilic substitution reaction wherein: R 2, R 4, R 5, R 6, R 7 R 8, R 10, R 11, R 13, W 1, W 3, X, Y, and n have the meanings defined above; (d) deprotecting an amino acid side chain protecting group in the compound of formula to obtain the salt of the β-turn peptidomimetic cyclic compound of formula; and (e) crystallizing the salt of the β-turn peptidomimetic cyclic compound of formula to obtain the compound of formula in crystalline form,