"chers messieurs, "
It is not recommended that a writer use "Dear Gentlemen's" in a salutation. "Dear gentlemen's" is referring to the gentlemen's object, not the men themselves. Try using "Dear gentlemen" instead.
I would recommend Ladies and Gentlemen.
The word "gentlemen" is generally not capitalized unless it is part of a title or heading. For example, you would write "The gentlemen at the meeting" but "Dear Gentlemen," in a letter. Always consider the context to determine if capitalization is appropriate.
The phrase "dear gentlemen" is grammatically correct, but it may sound a bit formal and old-fashioned. It is more common to address a group of people as "gentlemen" or "dear friends" instead.
'votre Cher roi'
Cher Monsieur is Dear Sir. if you know his name is Dupont, write Cher M. Dupont
The salutation is a from of greeting: Dear Mr. Smith: Dear Ms. Brown: Dear Professor Green: Dear Doctor Jones: Dear Professor Green and Ms. Brown: Dear Doctors Jones and Jacob: Dear Sir: Dear Madam: Dear Sir/Madam: Gentlemen: Ladies: Gentlemen and Ladies: To Whom It May Concern:
It seems only if your familiar, as 'dear' is a familiar term.
Welcome to the party, ladies and gentlemen.
"messieurs"
messieurs
Dear daughter is 'chère fille' in French.