An all-cis-functionalized cyclopropane template to connect the three peptid
e chains in a collagen model is designed. Stereoselective synthesis of cycl
opropane-assembled collagen-model 2b with the minimum unit of Gly-Pro-Pro i
s based on a novel 1-seleno-2-silylethene [2 + 1] cycloaddition strategy. R
eaction of the 1-seleno-2-silylethene 4 with triester-substituted olefin 5
in the presence of ZnI2 gives [2 + 1] cycloadduct 6 stereoselectively. Cycl
opropane 6 is selectively transformed into triol 10 in four steps. The reac
tion of 10 and three equivalents of N-Boc-Pro-Pro-Gly-OH in the presence WS
C-DMAP and subsequent deprotection with TFA gives 2b.