Looking for a more faithful translation of "...X, let alone Y"

Question

I am looking for a faithful translation of constructions like the following:

It will be a challenge to keep this collaboration alive, let alone productive.

The best I can think of is

Va a ser un desafío [reto?] mantener esta colaboración viva, ni hablar de productiva.

Is this understandable (let alone good!) Spanish?

Some background

Searching online for translations of the "let alone" construct in English, I often come across forms based on más or menos, usually qualified with an intensifying adverb like mucho, aún, or todavía. For example, using such a form, the above sentence could be translated as:

Va a ser un desafío mantener esta colaboración viva, y aún más [lo será] el mantenerla productiva.

This definitely is an adequate, workmanlike translation.

It is, nevertheless, charmless and "square". What is lost in this translation can be easily seen by translating it back to English as given, and comparing the two English versions:

It will be a challenge to keep this collaboration alive, and even more so [will be] to keep it productive.

I am hoping to find a translation to Spanish that avoids such dullness.

Answer 1

Great question.

Let me offer a suggestion: ni mucho menos.

We can compare the meaning of both expressions in the Oxford Dictionary, the English version for let alone and the Spanish version for ni mucho menos.

let alone

PHRASE
Used to indicate that something is far less likely or suitable than something else already mentioned.
He was incapable of leading a bowling team, let alone a country

ni mucho menos

PHRASE
Se utiliza para negar rotundamente algo, especialmente para añadir una negación rotunda a alguna negación anterior o presupuesta.
No me esperaba ni mucho menos esta respuesta; no me parecía una persona espontánea, y ni mucho menos alegre

It's not an exact match but notice that both expressions are used in relation with something previously mentioned, pointing that if A is rare to occur then far less likely (let alone/ni mucho menos) is B.

ni is used in the case of a previous negation. In your example there is no explicit negation so the suitable form would be: y mucho menos.

Va a ser un desafío mantener esta colaboración viva, y mucho menos productiva.

Answer 2

"Ni/y mucho menos", as suggested in the other answer is a very good translation.

As an alternative, let me suggest no digamos ya, which could be roughly translated as "not to mention", with a similar meaning to "let alone":

• Va a ser un desafío mantener esta colaboración viva, no digamos ya productiva.

As you can see on Reverso or Linguee, the expression "no digamos ya" is often translated as "let alone". This a somewhat informal expression and I would only use it in spoken speech.