Method for preparing chiral alkyl compounds by asymmetric hydrogenation of olefins catalyzed by iron complex

A method for preparing chiral alkyl compounds by asymmetric hydrogenation of olefins catalyzed by iron complex catalyst, wherein the method is as follows:

• reacting a disubstituted olefin shown in Formula I as a raw material, atmospheric hydrogen as hydrogen source, FeX2-8-OIQ complex as catalyst, hydrosilane and acetonitrile as co catalysts, for 12-24 hours under the activation of a reducing agent, to prepare a chiral alkyl compound shown in Formula II;
• wherein;
• in Formula II, * represents a chiral carbon atom;
• in Formula I or Formula II, R1 is C2˜C8 alkyl, naphthyl, a group shown in Formula III, or a N and O containing heterocyclic aryl group of C4˜C10;
• in R1, the H on C2˜C8 alkyl is not substituted or substituted by at least one substituent A, selected from the group consisting of and the substituent A is selected from the group consisting of phenyl, naphthyl, heterocyclic aryl or substituted phenyl;
• heterocyclic aryl is indolyl, pyridinyl, pyrrolyl, thiophenyl and furanyl;
• substituted phenyl is the phenyl group in which H on phenyl is replaced by at least one substituent B, and the substituent B is selected from the group consisting of C1˜C3 alkyl, C1˜C3 alkoxy, halogen and C1˜C3 alkylthio;
• in R1, the N and O containing heterocyclic aryl group of C4˜C10 is selected from the group consisting of pyridinyl, pyrrolyl, indolyl, benzodioxazolyl, benzoxazolyl and furanyl;
• in R1, the H on naphthyl and the N and O containing heterocyclic aryl group of C4˜C10 are not substituted or substituted by at least one substituent C, and the substituent C is C1˜C3 alkyl or C1˜C3 alkoxy;
• in R1, among the groups shown in Formula III, R4, R5, R6, R7, R8 are selected from the group consisting of H, halogen, C1˜C2 alkyl, C1˜C3 alkoxy, benzyloxy, C1˜C3 alkylthio, tert butyl dimethyl siloxy, trifluoromethyl, dimethylamino, pinacol borate, d-borneoxy, citronellol oxy, menthol oxy or geraniol oxy, and when R4, R5, R6, R7, R8 are all H, Formula III is phenyl;
• and halogen is F or Cl;
• in Formula I or Formula II, R2 is C1˜C8 alkyl, C2˜C8 alkenyl, phenyl or benzyl;
• the H on C1˜C8 alkyl and C2˜C8 alkenyl are not substituted or substituted by at least one substituent D selected from the group consisting of phenyl, substituted phenyl, C1˜C3 amino or 1,3-dioxolacyl;
• or in Formula I or Formula II, R1 and R2 are connected into a ring to form C9˜C12 benzocycloalkyl;
• H on C9˜C12 benzocycloalkyl is not substituted or substituted by at least one substituent E, and the substituent E is selected from the group consisting of C1˜C3 alkyl, C1˜C3 alkoxy or halogen;
• R1 and R2 are different substituents;
• wherein the catalyst FeX2-OIQ complex is an optically pure compound shown in Formula IV or its enantiomer or racemate;
• wherein in Formula IV, R9 is C1-C12 alkyl which is unsubstituted or substituted by one or two C1-C4 alkoxy, C5-C12 cycloalkyl which is unsubstituted or substituted by one to three substituents A, or aryl A which is unsubstituted or substituted by 1-4 substituents B;
• the aryl A is selected from the group consisting of benzyl, phenyl and naphthyl;
• the substituent A is selected from the group consisting of C1-C4 alkyl and C1-C4 alkoxy;
• and the substituent B is selected from the group consisting of C1-C4 alkyl, C1-C4 alkoxy, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, F and Cl;
• R10 is selected from the group consisting of H, C1-C12 alkyl which is unsubstituted or substituted by one or two C1-C4 alkoxy, C5-C12 cycloalkyl which is unsubstituted or substituted by 1-3 substituents A, or aryl B which is unsubstituted or substituted by 1-3 substituents A;
• the aryl B is phenyl or naphthyl;
• the substituent A is selected from the group consisting of C1-C4 alkyl and C1-C4 alkoxy;
• and the substituent B is selected from the group consisting of C1-C4 alkyl, C1-C4 alkoxy, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, F and Cl;
• R11, R12, R13, R14 and R15 are independently selected from the group consisting of H, C1-C12 alkyl, C1-C4fluoroalkoxy, F, CI, nitro and C5-C12 cycloalkyl which is unsubstituted or substituted by 1-3 substituents A;
• the substituent A is selected from the group consisting of C1-C4 alkyl and C1-C4 alkoxy;
• and the substituent B is selected from the group consisting of C1-C4 alkyl, C1-C4 alkoxy, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, F and Cl;
• R16 and R17 are independently selected from the group consisting of H and C1-C12 alkyl A which is unsubstituted or substituted by one or two C1-C4 alkoxy, C5-C12 cycloalkyl which is unsubstituted or substituted by 1-3 substituents A, or aryl A which is unsubstituted or substituted by 1-3 substituents B;
• the aryl A is selected from the group consisting of benzyl, phenyl and naphthyl;
• the substituent A is selected from the group consisting of C1-C4 alkyl and C1-C4 alkoxy;
• and the substituent B is selected from the group consisting of C1-C4 alkyl, C1-C4 alkoxy, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, F and Cl;
• R18 is selected from the group consisting of C1˜C12 alkyl group that is not substituted or substituted by 1-2 C1˜C4 alkoxy, C5-C12 cycloalkyl which is not substituted or substituted by 1-3 substituents A, or aryl A which is not substituted or substituted by 1-3 substituents B;
• the aryl A is selected from the group consisting of benzyl, phenyl and naphthyl;
• the substituent A is selected from the group consisting of C1-C4 alkyl and C1-C4 alkoxy;
• and the substituent B is selected from the group consisting of C1-C4 alkyl, C1-C4 alkoxy, C1-C4 fluoroalkyl, C1-C4 fluoroalkoxy, F and Cl;
• in Formula IV,* represents a chiral carbon atom;
• X is selected from the group consisting of F, Cl, Br, I, OAc and CF3SO3--;
• and wherein the reducing agent is selected from the groups consisting of sodium triethylborohydride, sodium tri-sec-butyl-borohydride, lithium triethylborohydride, sodium tert-butoxide, potassium tert-butoxide, lithium tert-butoxide, sodium tert-pentoxide, sodium ethoxide, sodium methoxide and potassium methoxide.