Android studio Gradle :: dependencies {compile 'com.android.support:appcompat-v7:18.0.0'} completes the compilation

Question

Android studio Gradle :: dependencies {compile 'com.android.support:appcompat-v7:18.0.0'} completes the compilation

I recently switched to android studio for development. I created a project with minsdk, tasksdk and compiled using sdk as Google Api Level 8.

The compilation of the project failed due to the following code in the build.gradle file.

dependencies {
    compile 'com.android.support:appcompat-v7:18.0.0'
}

Can someone tell me why this is happening?

All of my build.gradle is published below.

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:0.5.+'
    }
}
apply plugin: 'android'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 8
    buildToolsVersion "18.1.0"

    defaultConfig {
        minSdkVersion 8
        targetSdkVersion 8
    }
}

dependencies {
        compile 'com.android.support:appcompat-v7:18.0.0'
    }