Generated by SassMeister.com.

SassMeister-input-HTML.html

<nav>
	<a href="#" class="selected">Projects</a>
</nav>

SassMeister-input.scss

// ----
// Sass (v3.4.9)
// Compass (v1.0.1)
// ----

$colors: (
	red:#d21d0e,
	green:#77bb23,
	blue:#468ee5,
	yellow:#F5A623,
	purple:#9E0FBA,
	darkgreen:#7B9523
);

@each $color in $colors {
	$index: index($colors, $color);
	
	.select2-search-choice:nth-child(#{$index}) {
		background-color:$color;
		color:white;
	}
}

SassMeister-output.css

.select2-search-choice:nth-child(1) {
  background-color: red #d21d0e;
  color: white;
}

.select2-search-choice:nth-child(2) {
  background-color: green #77bb23;
  color: white;
}

.select2-search-choice:nth-child(3) {
  background-color: blue #468ee5;
  color: white;
}

.select2-search-choice:nth-child(4) {
  background-color: yellow #F5A623;
  color: white;
}

.select2-search-choice:nth-child(5) {
  background-color: purple #9E0FBA;
  color: white;
}

.select2-search-choice:nth-child(6) {
  background-color: darkgreen #7B9523;
  color: white;
}

SassMeister-rendered.html

<nav>
	<a href="#" class="selected">Projects</a>
</nav>