Converting an alcohol to an azide with S.sub.N 2 inversion using a phosphoryl azide

A process for converting an alcohol moiety to the corresponding azide with SN.sub.2 inversion comprising the step of:

• ##STR30## reacting said alcohol (I) with a phosphoryl azide (II) in a dry inert aprotic organic solvent in the presence of a proton acceptor, soluble in said solvent, at a temperature of about -20 to 100 degrees C., for a sufficient time to produce said azide (III), wherein the inverted carbon resulting from said SN.sub.2 inversion is indicated with an asterisk, wherein:
• (a) R.sub.1 is selected from the group consisting of C.sub.1 -C.sub.8 linear or branched alkyl, 5-10 membered monocyclic or bicyclic fused aromatic or heteroaromatic ring, wherein the hetero ring atoms are independently selected from the group consisting of nitrogen, sulfur and oxygen;
• wherein said aromatic or heteroaromatic ring can be substituted by 1-3 substituents X, Y or Z said substituents being independently selected from the group consisting of halo, trihalo-C.sub.1 alkyl, C.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.8 alkoxy, NH--CO-C.sub.1 -C.sub.8 alkyl, NH--CO-phenyl, NH--CO--OC.sub.1 -C.sub.8 alkyl, N(CO-C.sub.1 -C.sub.8 alkyl).sub.2, N(CO-phenyl).sub.2, O--CO-phenyl, or X and Y may be 1,2-methylenedioxy, without affecting the value of Z, wherein the C.sub.1 -C.sub.8 alkyl or phenyl moieties in said X, Y or Z substituents can in turn be substituted by 1-3 substituents independently selected from the group consisting of halo, C.sub.1 -C.sub.8 alkoxy and for phenyl, additionally the substituents can be, C.sub.1 -C.sub.8 alkyl;
• (b) R.sub.2 is selected from
• (i) --COOC.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.8 alkyl, C.sub.1 -C.sub.8 alkylcarbonyl;
• (ii) where R.sub.1 is an aromatic or heteroaromatic ring, R.sub.2 may further be ##STR31## where n is 1-5, R.sub.5 is hydrogen or C.sub.1 -C.sub.8 alkyl, or R.sub.1 and R.sub.2 are joined, such that together with the atoms to which they are attached there is formed a compound of the formula ##STR32## wherein G is C.sub.2 -C.sub.4 alkylene, which can be substituted with a C.sub.1 -C.sub.3 alkyl and said alkylene chain can contain a S(O).sub.n ring atom, where n is 0-2;
• (c) R.sub.3 and R.sub.4 are independently selected from C.sub.1 -C.sub.8 alkyl or phenyl, which can be substituted by 1-3 substituents of C.sub.1 -C.sub.8 alkoxy, halo, trihalo- C.sub.1 alkyl, and for phenyl, additionally C.sub.1 -C.sub.8 alkyl;
• wherein said process is carried out in the absence of dialkylazadicarboxylate.