[Arnfinn]

Hi. I have been working with a synthesis to create a disulfide bound on my molecule.I need to explain the details the reaction are as follows :

R-chOH-ch3 => R-ch(SC=OCH3)CH3

the reagents used in this reaction are the following :
Ph3P,DEAD,CH3COSH

can anyone explain for me what happends here? It seems for me that this is a substitution reaction where CH3COSH IS subsituted for OH. why are we using the other reagents dead and ph3P ?

IN the next step is as follows :

 R-ch(SC=OCH3)CH3 => R-ch(sh)ch3

the reagents used here is NaOCH3,MEOH, and hcl

is this just a basic hydrolysis of sulfuramide?
what are the roles of HCL? just to neutrelize the strong base NAOch3 ?

[Neecze]

Check out Mitsunobu reaction:

http://www.organic-chemistry.org/namedreactions/mitsunobu-reaction.shtm

[Doc Oc]

Neecze is correct, the first part of the reaction is a Mitsunobu.

For your 2nd question, yes, you are hydrolyzing the ester off of the sulfur group.  The NaOCH3 and MeOH are used for this purpose, so you are left with methyl acetate and the sulfur anion, which you quench at the end of the reaction with an acidic solution (HCl).