You should install libcouchbase first http://www.couchbase.com/communities/c/getting-started
wget -O- http://packages.couchbase.com/ubuntu/couchbase.key | sudo apt-key add -
sudo wget -O/etc/apt/sources.list.d/couchbase.list \
http://packages.couchbase.com/ubuntu/couchbase-ubuntu1204.list
sudo apt-get update
sudo apt-get install libcouchbase2-libevent libcouchbase-dev