The present invention provides methods of efficiently producing various optically active aromatic amino acid derivatives by reacting, using an additive, a specific ester compound with an aromatic halide and zinc in the presence of a catalyst. The present invention also provides amino acid derivatives that can be produced by the methods.

In one aspect, the invention relates to compounds having the formula:

##STR00001##

where R.sup.1-R.sup.6, a, b, Z, and X are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.

In one aspect, the invention relates to compounds having the formula:

##STR00001##

where R.sup.1-R.sup.6, a, b, Z, and X are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.

In one aspect, the invention relates to compounds having the formula I: ##STR00001##
where R.sup.1-R.sup.6 are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising these compounds; methods of using these compounds; and processes and intermediates for preparing these compounds.

In one aspect, the invention relates to compounds having the formula: ##STR00001##
where R.sup.1-R.sup.6, a, b, Z, and X are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.

In one aspect, the invention relates to compounds having the formula: ##STR00001##
where R.sup.1-R.sup.6, a, b, Z, and X are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising such compounds; methods of using such compounds; and processes and intermediates for preparing such compounds.

Disclosed in the present invention are a camptothecin derivative intermediate, and a preparation method therefor and the use thereof. The structural formula of the camptothecin derivative intermediate of the present invention is as shown in formula (I), and the definition of each substituent is as described in the description and claims. The intermediate (I) of the present invention can be used for preparing an intermediate (III), and can be further used for preparing exatecan and a derivative thereof. The preparation method of the present invention has the advantages of cheap and easily available raw materials, a novel method and simple route, mild conditions, a high yield, few by-products, suitability for scale-up synthesis and industrial production, etc.

##STR00001##

In one aspect, the invention relates to compounds having the formula I:

##STR00001##

where R.sup.1-R.sup.6 are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising these compounds; methods of using these compounds; and processes and intermediates for preparing these compounds.

In one aspect, the invention relates to compounds having the formula I: ##STR00001##
where R.sup.1-R.sup.6 are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising these compounds; methods of using these compounds; and processes and intermediates for preparing these compounds.

In one aspect, the invention relates to compounds having the formula I: ##STR00001##
where R.sup.1-R.sup.6 are as defined in the specification, or a pharmaceutically acceptable salt thereof. These compounds have neprilysin inhibition activity. In another aspect, the invention relates to pharmaceutical compositions comprising these compounds; methods of using these compounds; and processes and intermediates for preparing these compounds.