What would happen if we connect 2 asynchronous grids through an AC link? Will they come to synchronization?

Probably not. Typically you need to synchronize first then close the breaker.

Hamish is right, but maybe you would like a fuller explanation.

Try this in SPICE: Define two sine waves, one being the voltage of each Grid. Then subtract them in a behavioral voltage source. Unless they are identical, voltage, frequency, phase, you will see a voltage difference waveform. If you know the impedance of the ac link, ohms law will tell you the current that will flow. It's probably huge, enough to open breakers and/or destroy stuff.

If it survives all that, they will be forced to synchronize. It might be possible to connect them, with care, if one grid can conform to the other very rapidly, without large transients. That is not likely unless it was designed specifically to do that.

I agree with the previous two postings, but would like to add a little more information.
Ideally when connecting two AC grids together a number of parameters need to be matched. First of all the voltage magnitude of the two grids needs to be matched. Secondly, the frequency needs to be made the same. Finally, before closing any breakers, the phase angle of the two grids needs to be made the same. Under these circumstances there should be a very small (ideally zero) current flowing between the breakers during its closing. It is important to follow this line synchronization procedure, otherwise very large currents can flow, and potentially trip the circuit breakers or even damage the system.
The process I described is similar to how utilities connect large generators to the AC grid. They also monitor the voltage across each of the open breaker phases, when the procedure is followed, and the voltage across each of the breaker phases stays near zero, then it is the proper time to close the breaker.
If it is a multiphase system, then it is also important to make sure you have a proper phase sequence connection.
If you just connect two systems together, without following the procedure I described, then extremely large transient currents can flow when the systems are interconnected. The magnitude of the transient depends upon how mismatched the grid parameters (voltage, frequency, phase) are, and the impedance of the grids.