Process for producing optically active phosphorus heterocyclic dimer

A process for producing a phosphorus heterocyclic dimer according to formula (5) comprising the steps of:

• reacting, in the presence of a n-butyl lithium, primary phosphine represented by formula (1):
• R—PH2 (1)
• (wherein R represents a linear or a branched alkyl group having 2 to 20 carbon atoms or a cyclic alkyl group having 3 to 20 carbon atoms) with a compound represented by formula (2):
• Y—CnH2n—Y (2)
• (wherein Y represents a halogen atom or a leaving group selected from -OTs, -OTf, and -OMs, and n represents a number of 3 to 6);
• reacting a product, which was obtained by said step of reacting primary phosphine represented by formula (1) with a compound represented by formula (2), with boron trihydride, oxygen, or sulfur to obtain a phosphorus heterocyclic compound represented by formula (3):
• (wherein R represents a linear or a branched alkyl group having 2 to 20 carbon atoms or a cyclic alkyl group having 3 to 20 carbon atoms, n equals 1, X represents a boron trihydride group, an oxygen atom, or a sulfur atom, and ═══ represents a single bond when X is a boron trihydride group or a double bond when X is an oxygen atom or sulfur atom);
• dimerizing the phosphorus heterocyclic compound represented by formula (3) to produce a phosphorus heterocyclic dimer represented by formula (4):
• (wherein R represents a linear or a branched alkyl group having 2 to 20 carbon atoms or a cyclic alkyl group having 3 to 20 carbon atoms, n equals 1, X represents a boron trihydride group, an oxygen atom, or a sulfur atom);
• and
• removing oxygen, sulfur, or borane from the phosphorus heterocyclic dimer represented by formula (4) to obtain an optically active phosphorus heterocyclic dimer represented by formula (5):
• wherein R represents a linear or a branched alkyl group having 2 to 20 carbon atoms or a cyclic alkyl group having 3 to 20 carbon atoms, n equals 1);
• and
• wherein the compound represented by formula (2) is 1,3-dichloropropane.