Process for preparing methyl phosphinic acid butyl ester

A process for preparing the compound of the formula (V):

• wherein
• R is C1-C6 alkyl or benzyl, and R1 is C1-C6 alkyl,
• comprising the steps of:
• (a) reacting hypophosphorous acid with a C1-C6 alkyl or benzyl alcohol in the presence of an acid under dehydrating conditions in a non-polar solvent to obtain the compound of formula (I)
• wherein R is C1-C6 alkyl or benzyl;
• (b) reacting the compound obtained in step (a) with a trialkyl orthoformate to obtain the compound of formula (II):
• wherein R2 is O-alkyl;
• (c) reacting the compound obtained in step (b) with an alkylating agent in the presence of a base to obtain a compound of formula (III):
• wherein R is C1-C6 alkyl or benzyl;
• R1 is C1-C6 alkyl;
• and R2 is O-alkyl;
• (d) reacting the compound obtained in step (c) with an acid to obtain a compound of formula (IV):
• wherein R1 is C1-C6 alkyl;
• (e) reacting the compound obtained in step (d) with an alkyl alcohol in the presence of an acid under dehydrating conditions in a non-polar solvent to obtain the compound of formula (V);
• or for preparing compound of the formula (IV):
• wherein
• R is C1-C6 alkyl or benzyl, and R1 is C1-C6 alkyl, comprising the steps of:
• (a) reacting hypophosphorous acid with a trialkyl orthoformate to obtain the compound of formula (I):
• wherein each R2 is O-alkyl;
• (b) reacting the compound obtained in step (a) with an alkylating agent in the presence of a base to obtain the compound of formula (II):
• wherein R1 is C1-C6 alkyl or benzyl;
• and each R2 is O-alkyl;
• (c) reacting the compound obtained in step (b) with an acid to obtain the compound of formula (III):
• wherein R1 is C1-C6 alkyl;
• (d) reacting the compound obtained in step (c) with a C1-C6 alkyl alcohol or benzyl alcohol in the presence of an acid under dehydrating conditions in a non-polar solvent to obtain the compound of formula (IV).

A process for preparing the compound of the formula (II)

• wherein
• R is C1-C6 alkyl or benzyl, and R1 is C1-C6 alkyl,
• comprising the steps of:
• (a) reacting hypophosphorous acid with a C1-C6 alkyl or benzyl alcohol in the presence of an acid under dehydrating conditions to obtain the compound of formula (I)
• wherein
• R is C1-C6 alkyl or benzyl;
• and
• (b) reacting the compound obtained in step (a) with an alkylating agent in the presence of a base to give the compound of formula (II).