The stereoselectlve synthesis 01 1SOVallne (2-amino-2-methylbutyrlc acla) and the stereocncmlcal pathway vla the key Intermedlatc 2 Is descrlbcd For use In peptlde synthesis, thls a,a-dlalkyl amlno acid Is incorporated into N-protected dlpeptlde derlvatlves In high yields. Special emphasis was put on the upscallng-problem Due to their pronounced hellx-lnduclng potential, some a.a-alalxyl amino acias have attracted great attention In the design 01 peptlaes with tallor-made conlormatlonal features2 Several routes for the stereoselectlve synthesls 01 these conlormatlonally constrarned amlno acids have been reported over the last few years.3 However, COnvenlent methods for the preparation in large scale needed for their Incorporation into peptides are St111 .lacklng.4 We describe here an efficient procedure for the synthesls 01 both enantlomen 01 ISOValtne, the optIcally active homologue 01 the well-known Aibs Further, thelr conversion into ootlcally active dlpeptlde derlvatlves which are key Intermedlates In oeptlde chemistry Is reported.6 Thls synthesls takes advantage 01 the "prlnclple 01 sell reproduction of cnlrallty centers', introduced by Seebach et al 3, a strategy exhlbltlng some lavourable features. Both enantlomers 01 the ammo