What is the voltage drop across resistor in this circuit?
re:  "In my opinion there must be some voltage through R1 and because of that the voltage 0.6V don't "flow" to the anode of D2.

Am I missing something here? The sinewave signal injected in 'in' doesn't generate a drop through R1?"

The valid current paths are:

A.  R3-->D1-->gnd
B.  R3-->R1-->D2-->R2-->Gnd
Note:  D2 must be forward biased (i.e. conducting) for current to flow through R2

The voltage drop across R1 will depend on the input signal voltage.  When the input signal V is too low, D2 will not become forward biased.

There is .6V at the bottom of R1.  If the +in V is high enough, it will add to the voltage that has passed through R1 and the combined V will be sufficient to cause D2 to become forward biased.  Once D2 is fb, current will flow through R2 to gnd.