Attempted recreation of @anuteja 's problem.

problem.component.ts

//Working towards a minimal demonstration of the problem.
//This currently works as expected :(
import { Component } from '@angular/core';
@Component({
  moduleId: module.id,
  selector: 'problem',
  styles: [`
    .original { color: green; }
    .different { color: orange; }
  `],
  template: `
    <div *ngFor="let n of [1,2,10]" [ngClass]="myClass">
      hello world {{n}}
    </div>
    <button (click)="changeClass()">Change Class</button>`
  })
export class ProblemComponent {

  myClass = "original";

  changeClass() {
    this.myClass = "different";
  }
}