handle checkbox with "new FormControl"

Basically I do not know how to handle this topic from an *ngFor where there is checkbox. I would normally know how to do it with a [(ngModel)], but I do not know how to do it with reactive forms. I want to associate my checkbox according to what I have in the variable "aUsers" and mark the elements that I have in the "check" attribute. what should I do?

this.ValidacionReunion = new FormGroup({
  observaciones:new FormControl(null, []),
  arrayElements: new FormControl.array([])  //this is the name of my checkboxlist
});

aUsers:any=
[
  {
    "name":"xds",
    "userusuario":2,
    "check":true
  },
  {
    "name":"xdsx",
    "iduser":2,
    "check":false
  }      
]

. . .

<!-- obviously this is inside:<form [formGroup] = "ValidationReunion"> -->
<li  class="list-group-item waves-light"  *ngFor="let user of aUsers" >
 <input type="checkbox" formControlName="user.check">       
</li>