Process for the preparation of tetrazole derivatives from organo aluminium azides

1. A process for the manufacture of a compound of formula (IV b)

or a tautomer or a salt thereof,

characterized by

(i) reacting a compound of formula (IV c)

or an ester thereof, with a an azide compound of formula (R 1 )(R 2 )M-N 3 (II b), wherein R 1 and R 2 , independently

represent an organic residue selected from the group consisting of an aliphatic residue, an alicyclic residue, a heteroalicyclic residue; an alicyclic-aliphatic residue; a heteroalicyclic-aliphatic residue; a carbocyclic and a heterocyclic aromatic residue; an araliphatic residue or an heteroaraliphatic residue, each residue, independently of another; and M is boron or aluminium;

wherein,

an aliphatic residue is C 1 -C 20 alkyl, C 3 -C 20 alkenyl or C 3 -C 20 alkynyl, each of which can be interrupted by NH, substituted NH, O, or S;

an alicyclic residue is mono-, bi- or polycyclic, selected from the group consisting of C 3 -C 8 cycloalkyl and C 3 -C 7 cycloalkenyl;

a heteroalicyclic residue is an alicyclic residue, wherein at least one carbon atom is replaced by a heteroatom selected from the group consisting of NH, substituted NH, O, and S;

an alicyclic-aliphatic residue is C 1 -C 20 alkyl, C 3 -C 20 alkenyl or C 3 -C 20 alkynyl that is substituted by C 3 -C 8 cycloalkyl or by C 3 -C 7 cycloalkenyl;

a heteroalicyclic-aliphatic residue is C 1 -C 8 -alkyl, C 2 -C 8 -alkenyl or C 2 -C 8 -alkynyl each of which substituted by C 3 -C 8 cycloalkyl or by C 3 -C 8 -cycloalkenyl wherein one carbon atom of C 3 -C 8 cycloalkyl or C 3 -C 8 -cycloalkenyl, respectively, is replaced by NH, substituted NH, O, or S;

a carbocyclic aromatic residue selected from the group consisting of moncyclic, bicyclic and polycyclic, or benzoanellated carbocyclic residue;

a heterocyclic aromatic residue is 5- or 6-membered and monocyclic radical which has up to four identical or different hetero atoms, selected from the group consisting of nitrogen, oxygen and sulfur atoms, preferably one, two, three or four nitrogen atoms, an oxygen atom or a sulfur atom;

an araliphatic residue is C 1 -C 8 -alkyl, C 2 -C 8 -alkenyl or C 2 -C 8 -alkynyl each of which is substituted by phenyl or by naphthyl;

an heteroaraliphatic residue is C 1 -C 8 -alkyl, C 2 -C 8 -alkenyl or C 2 -C 8 -alkynyl each of which is substituted by pyrazolyl, imidazolyl, triazolyl, tetrazolyl, furyl, thienyl or pyridyl; and

substituted NH is NH which is substituted by C 1 -C 8 -alkyl, phenyl-C 1 -C 8 -alkyl, C 2 -C 8 -alkyl-alkanoyl, phenyl-C 2 -C 5 -alkanoyl, benzoyl, C 1 -C 8 -alkanesulfonyl or benzenesulfonyl; l

and M is boron or aluminium; and

(ii) isolating the resulting compound of formula (IV b).

2. A process according to claim 1 , wherein a compound of formula (R 1 )(R 2 )M-N 3 (II b) is used, wherein M is aluminium or boron; and R 1 and R 2 , independently of one another, is C 1 -C 8 -alkyl; C 3 -C 7 alkenyl, C 3 -C 7 -cycloalkyl; phenyl-C 1 -C 4 -alkyl; phenyl-C 3 -C 5 alkenyl, or C 3 -C 8 -cycloalkyl-C 1 -C 8 -alkyl.

3. A process according to any claim 1 , wherein a compound of formula (R 1 )(R 2 )M-N 3 (II b) is used, wherein M is aluminium or boron: and R 1 and R 2 , independently of one another, is C 1 -C 8 -alkyl, C 3 -C 8 -cycloalkyl, C 3 -C 8 -cycloalkyl-C 1 -C 8 -alkyl or aryl-C 1 -C 8 -alkyl.

4. A process according to claim 1 , wherein a compound of formula (R 1 )(R 2 )M-N 3 (II b) is selected from the group consisting of: dimethyl aluminium azide, diethyl aluminium azide, diisopropyl aluminium azide, dipropyl aluminium azide, diisobutyl aluminium azide, dibutyl aluminium azide, dicyclohexyl aluminium azide, diethyl boron azide, diisopropyl boron azide, dipropyl boron azide, diisobutyl boron azide, dibutyl boron azide, dicyclohexyl boron azide, and diphenyl boron azide.

5. A process according to claim 1 , wherein the compound of formula (R 1 )(R 2 )M-N 3 (II b), wherein M is aluminium or boron; and R 1 and R 2 , independently of one another, C 3 -C 7 alkenyl which is allyl or crotyl, C 3 -C 7 -cycloalkyl which is cyclohexyl; phenyl-C 1 -C 4 -alkyl which is benzyl or 2-phenethyl; phenyl-C 3 -C 5 alkenyl which is cinnamyl, or C 3 -C 8 -cycloalkyl-C 1 -C 8 -alkyl which is cyclopropylmethyl or cyclohexylmethyl.

6. A process according to claim 1 wherein the ester of a compound of formula (IVc) is an ester derived from an aliphatic or araliphatic alcohol, wherein

the aliphatic residue is C 1 -C 20 -alkyl, C 2 -C 20 -alkenyl or C 2 -C 20 -alkynyl, each of which can be interrupted by NH, O, S or NH which is substituted by C 1 -C 8 -alkyl, phenyl-C 1 -C 8 -alkyl, C 2 -C 8 -alkyl, C 2 -C 10 -alkanoyl, phenyl-C 2 -C 5 -alkanoyl, benzoyl, C 1 -C 8 -alkanesulfonyl or benzenesulfonyl; and

the araliphatic residue is C 1 -C 8 -alkyl, C 2 -C 8 -alkenyl or C 2 -C 8 -alkynyl each of which is substituted by phenyl or naphthyl.

7. A process according to claim 1 , wherein an ester of a compound of formula (IVc) is an ester derived from an aliphatic or araliphatic alcohol, wherein

an aliphatic residue is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-propenyl, 2-butenyl, 3-butenyl or propargyl, each of which can be interrupted by NH, O, S or NH which is substituted by C 1 -C 8 -alkyl, phenyl-C 1 -C 8 -alkyl, C 2 -C 8 -alkyl-C 2 -C 10 -alkanoyl, phenyl-C 2 -C 5 -alkanoyl, benzoyl, C 1 -C 8 -alkanesulfonyl or benzenesulfonyl; and

an araliphatic residue is benzyl, 2-phenethyl or 2-phenyl-ethenyl.

8. A process according to claim 1 wherein the ester of a compound of formula (IVc) is an ester derived from an aliphatic or araliphatic alcohol, wherein

an aliphatic residue is methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, 2-propenyl, 2-butenyl, 3-butenyl or propargyl; and

an araliphatic residue is benzyl, 2-phenethyl or 2-phenyl-ethenyl.

9. A process according claim 1 , wherein an ester of a compound of formula (IVc) is a C 1 -C 7 alkyl ester or a benzyl ester thereof.

10. A process according to claim 1 , wherein an ester of a compound of formula (IVc) is a benzyl ester thereof.