The invention provides methods of preparing macrocycles including macrocycle stabilized peptides (MSPs). Macrocycles and MSPs are prepared according to nucleophilic capture of an iminoquinomethide type intermediate generated from a suitably substituted 2-amino-thiazol-5-yl carbinol. The preferred nucleophile may be selected from an electron rich aromatic moiety in the case of macrocycles and, in the case of MSPs, at least one amino acid comprises an electron rich aromatic moiety. In addition, the concept can be extended to other related 5-membered heterocyclic systems in place of the thiazole, such as imidazole or oxazole. The conditions for the generation of the corresponding iminoquinomethide type intermediates may be similar or different than the conditions used for the 2-amino-thiazol-5-yl carbinol.