... Dale L. Boger*' and Daniel Yohannes Department of Chemistry and Medicinal Chemistry, Purdue University, West Lafayette, Indiana 47907 Received July 28, 1987 The total synthesis of cyclo-(~-Ala-Ala-N-Me-Tyr(OCH~)-Ala-N-Me-Tyr-N-Me-~r) ... Page 4. 490 J. Org. Chem., Vol. ...