Coffeescript string interpolation behavior

first_name = "Matt"
full_name1 = "#{first_name } Boler"
console.log(full_name1)

My understanding is that this is supposed to concatenate the strings and print out

Matt Boler

to the terminal. Instead, it prints out

#{first_name1} Boler

What am I missing? This is being done on windows with node.js