<===> input.scss
.media-object-section:last-child:not(:nth-child(2)) {
  color: blue;
}

%orbit-control {
  color: red;
}

.orbit-previous {
  @extend %orbit-control;
}

<===> output.css
.media-object-section:last-child:not(:nth-child(2)) {
  color: blue;
}

.orbit-previous {
  color: red;
}