How i can write to a bit field in IDE CWide eTPU?

Hi, i'm using CWide or codewarrior for eTPU and when i create for example a struct:

typedef union

{

   struct

   {

      uint32_t B0:1;

      uint32_t B1:1;

      uint32_t B2:2;

      uint32_t B3:4;

      uint32_t B4:8;

      uint32_t B5:16;

   }B;

   uint32_t R;

}EST;

EST Est;

if i write Est.R = 1<<30; works but when Est.B1 = 1; that's not works.

If posible write a bit like that?