Claims
- 1. A process for preparing a compound of formula (I): ##STR13## or a salt of carboxylic acid or ester thereof, which process comprises reacting a compound of formula (II): ##STR14## wherein R.sup.x is a carboxy-protecting group with (i) isocyanic acid;
- (ii) a compound of formula (III):
- R.sup.1 OCON=NCOOR.sup.2 (III)
- wherein R.sup.1 and R.sup.2 are each independently C.sub.1-6 alkyl, aryl or aryl (C.sub.1-6) alkyl; and
- (iii) a compound of formula (IV): ##STR15## wherein l, m and n are each independently 0 or 1, and R.sup.3, R.sup.4 and R.sup.5 are each independently C.sub.1-6 alkyl, aryl or aryl (C.sub.1-6) alkyl;
- and thereafter, where necessary, carrying out one or more of the following steps:
- (a) removing the carboxy-protecting group R.sup.x ; and/or
- (b) converting a salt to the free carboxylic acid of formula (I) or to an ester, or to a different salt.
Parent Case Info
This application is a divisional of U.S. Ser. No. 530,752, filed on Sept. 9, 1983, U.S. Pat. No. 4,622,177.
Non-Patent Literature Citations (3)
Entry |
Loibner et al., Helv. Chim. Acta. 59, 2100 (1976). |
Sykes, "A Guidebook to Mechanism on Organic Reactions", p. 63 (1965). |
Whitfield, "A Guide to Understanding Basic Organic Reactions", (1966). |
Divisions (1)
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Number |
Date |
Country |
Parent |
530752 |
Sep 1983 |
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