| 摘要 |
The invention provides salts of formula (I) wherein X is a basic counterion selected from a group I or group II metal and a primary, secondary or tertiary amine; n is 0, 1 or 2; and R<1>, R<1a>, R<2>, R<2a>, R<3>, R<3a>, R<4 >and R<4a >are independently selected from H and C1-C6 alkyl, or R<1 >and R<2 >or R<2 >and R<3 >are taken together to form a C3-C7 cycloalkyl ring, which is optionally substituted with one or two substituents selected from C1-C6 alkyl, which are useful as intermediates in the preparation of cyclic and bicyclic amino acids. Processes for the preparation of the final products and for the conversion of the compounds of formula (I) to amino acids are included.
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