How can one run multiple programs in the background with single command?

From a shell syntax point of view, & separates commands like ;/|/&&... (though of course with different semantic). So it's just:

cmd1 & cmd2 & cmd3 &

The bash manpage section titled Compound Commands has two options that would work, list and group commands.

A group command is a series of commands enclosed in curly braces {}. A list is the same, enclosed in parentheses (). Both can be used to background multiple commands within, and finally to background the entire collection as a set. The list construct executes commands in a subshell, so variable assignments are not preserved.

To execute a group of commands:

{ command1 & command2 & } &

You can also execute your commands in a list (subshell):

( command1 & command2 ) &

another way:

$(command1 &) && command2 &