摘要:
This invention provides an improved process for producing azetidinones. More particularly, this invention provides the steps of producing an trans-azetidinone represented by the formula ##STR1## from a carboxylic acid R.sup.2 --D--CH.sub.2 COOH, an aldehyde R.sup.1 --A--CHO and an amine RNH.sub.2, by the steps of: (a1) converting a carboxylic acid to the corresponding acid chloride; (b1) deprotonating a chiral oxazolidinone and treating the resulting anion with the product of step (a1); (c1) enolizing the product of step (b1) and condensing with the aldehyde; (d1) hydrolyzing the product of step (c1); (e1) condensing the product of step (d1) with the amine; and (f1) cyclizing the product of step (e1). Alternatively, the process comprises (a2) enolizing the product of step (b1) and condensing, in the presence of a Lewis acid, with a Schiff's base prepared from the aldehyde and the amine; and (b2) cyclizing the product of step (a2).
摘要:
This invention provides an improved process for producing azetidinones. More particularly, this invention provides the steps of producing an trans-azetidinone represented by the formula ##STR1## from a carboxylic acid R.sup.2 -D-CH.sub.2 -COOH, an aldehyde R.sup.1 -A-CHO and an amine RNH.sub.2, by the steps of: (a1) converting a carboxylic acid to the corresponding acid chloride; (b1) deprotonating a chiral oxazolidinone and treating the resulting anion with the product of step (a1); (c1) enolizing the product of step (b1) and condensing with the aldehyde; (d1) hydrolyzing the product of step (c1); (e1) condensing the product of step (d1) with the amine; and (f1) cyclizing the product of step (e1).Alternatively, the process comprises (a2) enolizing the product of step (b1) and condensing, in the presence of a Lewis acid, with a Schiff's base prepared from the aldehyde and the amine; and (b2) cyclizing the product of step (a2).
摘要:
Described is a process for the regioselective dehydration of 11-hydroxy steroids using PCl.sub.5, PCl.sub.3, POCl.sub.3 or either SO.sub. Cl.sub.2 and imidazole, or PPh.sub.3 and CCl.sub.4. The disclosed process selectively forms .increment..sup.9,11 steroids from either 11-.alpha.- or 11-.beta.-hydroxy steroids, and can also be used for the one-step conversion of 11,21-dihydroxy steroids to 21-chloro-.increment..sup.9,11 steroids.
摘要:
Described is a process for the regioselective dehydration of 11-hydroxy steroids using PCl.sub.5, PCl.sub.3, POCl.sub.3 or either SO.sub.2 Cl.sub.2 and imidazole, or PPh.sub.3 and CCl.sub.4. The disclosed process selectively forms .DELTA..sup.9,11 steroids from either 11-.alpha.- or 11-.beta.-hydroxy steroids, and can also be used for the one-step conversion of 11,21 -dihydroxy steroids to 21-chloro-.DELTA..sup.9,11 steroids. Also disclosed are processes for the regioselective conversion of 11-.beta.-chloro steroids to .DELTA..sup.9,11 steroids, and for regioselectively converting an 11,17,21-trihydroxy streoid to a 21-chloro-11,17-dihydroxy steroid.
摘要:
The preparation of arylethanolamines, and in particular albuterol (salbutamol), together with their novel boron, acetal and hemi-acetal intermediates is described.
摘要:
The invention relates to a crystalline form of a triethylamine salt of (2Z)-2-(2-amino-5-chlorothiazol-4-yl)-2-(3-N-tert-butoxycarbonylaminopropoxyimino)acetic acid. The invention also relates to processes and intermediates for preparing the crystalline form. The crystalline form is useful as an intermediate for preparing cross-linked glycopeptide-cephalosporin antibiotics.
摘要:
Disclosed are processes for preparing glycopeptide antibiotic derivatives having an amino-containing side chain. The multi-step process is conducted in a single reaction vessel without isolation of intermediate reaction products.
摘要:
Disclosed are processes for preparing glycopeptide antibiotic derivatives having an amino-containing side chain. The multi-step process is conducted in a single reaction vessel without isolation of intermediate reaction products.
摘要:
Disclosed are processes for preparing glycopeptide phosphonate derivatives having an amino-containing side chain. Several of the process steps are conducted in a single reaction vessel without isolation of intermediate reaction products, thereby generating less waste and improving the overall efficiency and yield of the process.
摘要:
A process is described for preparing 3-exomethylene cephalosporanic acid derivatives for use in the synthesis of cephalosporin antibiotics such as ceftibuten. The process comprises electrochemical reduction of a compound of the formula (IV) ##STR1## wherein: R.sup.3 is CH.sub.3 C(O)--; ##STR2## is an optional sulfoxide group; n is 2 or 3; R.sup.1 is H and R is H or NHR.sup.2, where R.sup.2 is H or a protecting group selected from C.sub.6 H.sub.5 CH.sub.2 OC(O)--, C.sub.6 H.sub.5 C(O)-- or C.sub.1 -C.sub.6 alkoxy-C(O)--; or wherein R and R.sup.1 together with the carbon atom to which they are attached comprise --C(O)--, and produces the desired 3-exomethylene compounds with low levels of the corresponding 3-methyl tautomers.