SPPS base-labile resins

Our group has initiated a project to search for milder methods for the preparation of organometallic peptide conjugates by SPPS. By using a base-labile linker to the resin and suitable side-chain protecting groups, we were able to prepare acid-sensitive organometallics amendable to SPPS techniques. As an example, enkephalin derivatives with the covalently bound Mo(allyl)(GO)2 moiety such as 17 were successfully prepared (Scheme 19). An attractive... 

The two major chemistries for SPPS involve the use of either base labile a-amino protecting group (Fmoc) or acid labile a-amino protecting group (Boc). Each method involves different side chain protecting group, and consequent cleavage/deprotection methods and resins (Table 1). 

Sorbus and Crataegus spp. Used for manuf. of sorbose, propylene glycol, ascorbic acid, resins, plasticisers and as antifreeze mixts. with glycerol or glycol. Tablet excipient, sweetening agent and humectant. Used in photometric detn. of Ru(K/) and Ru(F//7) in acid-base titration of borate. Needles -f- 5 or IHjO (EtOH) with sweet taste (60% of sucrose). Freely sol. H2O fairly sol. hot EtOH spar. sol. cold EtOH. Mp 97° (stable form), Mp 92° (labile form), Mp 110-112° (anhyd.). [a] +7° (borax), [a]j 4-31° (molybdate). pA 13.00 (60°). 

---