Method for hydroformylation, xanthene-bridged ligands and catalyst comprising a complex of said ligands

A process as claimed in either of the preceding claims, wherein the compound of the formula I is selected from among compounds of the formulae I.1 to I.6

• 14 15
• where
• A1 is O, S or CR5R6, where R5 and R6 are each, independently of one another, hydrogen or C1-C4-alkyl,
• R17, R18, R19, R20, R21, R22, R23 and R24 are each, independently of one another,
• hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COORf, COO−M+, SO3Rf, SO−3M+, NE4E5, alkylene-NE4E5, NE4E5E6+X−, alkylene-NE4E5E6+X−, ORf, SRf, (CHRgCH2O)yRf, (CH2N(E4))yRf, (CH2CH2N(E4))yRf, halogen, trifluoromethyl, nitro, acyl and cyano,
• where
• Rf, E4, E5 and E6 are identical or different radicals selected from among hydrogen, alkyl, cycloalkyl and aryl,
• Rg is hydrogen, methyl or ethyl,
• M+is a cation,
• X− is an anion, and
• y is an integer from 1 to 120.

A compound of the formula I

• 16
• where
• A1 and A2 are each, independently of one another, O, S, SiRaRb, NRcor CR5R6, with the exception of A1=S and A2=O, where
• Ra, Rb, Rc, R5 and R6 are each, independently of one another, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl,
• y1 and y2 are each, independently of one another, radicals containing at least one phosphorus atom, where in each case at least two substituted or unsubstituted heteroatoms selected from among O, S and NRc, where Rc is hydrogen, alkyl, cycloalkyl or aryl, are directly bound to the phosphorus atom, and
• y1 and y2 are each, independently of one another, a radical of the formula P(OR7)(OR8), OP(OR7)R8 or OP(OR7)(OR8), where
• R7 and R8 are each, independently of one another, cycloalkyl, heterocycloalkyl, aryl or hetaryl which may bear one, two or three substituents selected from among alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COORf, COO−M+, SO3Rf, SO−3M+, NE4E5, alkylene-NE4E5, NE4E5E6+X−, alkylene-NE4E5E6+X−, ORf, SRf, (CHRgCH2O)yRf, (CH2N(E4))yRf, (CH2CH2N(E4))yRf, halogen, trifluoromethyl, nitro, acyl and cyano,
• where
• Rf, E4, E5 and E6 are identical or different radicals selected from among hydrogen, alkyl, cycloalkyl or aryl,
• Rg is hydrogen, methyl or ethyl,
• M+is a cation,
• X− is an anion, and
• y is an integer from 1 to 120, or
• R7 and R8 together with the phosphorus atom and the oxygen atom(s) to which they are bound form a 5- to 8-membered heterocycle to which one, two or three cycloalkyl, heterocycloalkyl, aryl or hetaryl groups may additionally be fused, where the heterocycle and, if present, the fused-on groups may each bear, independently of one another, one, two, three or four substituents selected from among alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COORf, COO−M+, SO3Rf, SO−3M+, NE4E5, alkylene-NE4E5, NE4E5E6+X−, alkylene-NE4E5E6+X−, ORf, SRf, (CHRgCH2O)yRf, (CH2N(E4))yRf, (CH2CH2N(E4))yRf, halogen, trifluoromethyl, nitro, acyl and cyano, where Rf, Rg, E4, E5, E6, M+, X− and y are as defined above,
• R1, R2, R3 and R4 are each, independently of one another, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COORd, COO−M+, SO3Rd, SO−3M+, NE1E2, NE1E2E3+X−, alkylene-NE1E2E3+X−, ORd, SRd, (CHReCH2O)xRd, (CH2N(E1))xRd, (CH2CH2N(E1))xRd, halogen, trifluoromethyl, nitro, acyl or cyano,
• where
• Rd, E1, E2 and E3 are identical or different radicals selected from among hydrogen, alkyl, cycloalkyl and aryl,
• Re is hydrogen, methyl or ethyl,
• M+is a cation,
• X− is an anion, and
• x is an integer from 1 to 120, or
• R1 and/or R2 together with two adjacent carbon atoms of the benzene ring to which they are bound form a fused ring system having 1, 2 or 3 further rings.

A catalyst comprising at least one complex of a metal of transition group VIII with at least one ligand selected from among compounds of the formula I

• 17
• where
• A1 and A2 are each, independently of one another, O, S, SiRaRb, NRc or CR5R6, with the exception of A1=S and A2=O, where
• Ra, Rb, Rc, R5 and R6 are each, independently of one another, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl or hetaryl,
• y1 and y2 are each, independently of one another, radicals containing at least one phosphorus, arsenic or antimony atom, where in each case at least two substituted or unsubstituted heteroatoms selected from among O, S and NRc, where Rc is hydrogen, alkyl, cycloalkyl or aryl, are directly bound to the phosphorus, arsenic or antimony atom, and
• R1, R2, R3 and R4 are each, independently of one another, hydrogen, alkyl, cycloalkyl, heterocycloalkyl, aryl, hetaryl, COORd, COO−M+, SO3Rd, SO−3M+, NE1E2, NE1E2E3+X−, alkylene-NE1E2E3+X−, ORd, SRd, (CHReCH2O)xRd, (CH2N(E1))xRd, (CH2CH2N(E1))xRd, halogen, trifluoromethyl, nitro, acyl or cyano,
• where
• Rd, E1, E2 and E3 are identical or different radicals selected from among hydrogen, alkyl, cycloalkyl and aryl,
• Re is hydrogen, methyl or ethyl,
• M+is a cation,
• X− is an anion, and
• x is an integer from 1 to 120, or
• R1 and/or R2 together with two adjacent carbon atoms of the benzene ring to which they are bound form a fused ring system having 1, 2 or 3 further rings.