A-Hydroxy imidates

TABLE 6.8. 5-ARYL-2,4-OXAZOLIDINEDIONES EROM CYCLIZATION OE a-HYDROXY IMIDATES ... 

TABLE 6.9. SPIROCYCLIC 2,4-OXAZOLIDINEDIONES EROM CYCEIZATION OE a-HYDROXY IMIDATES"... 

TABLE 6.9 SPIROCYCLIC 2,4-OXAZOLIDINEDIONES FROM CYCLIZATION OF a-HYDROXY IMIDATES, 101... 

A-Hydroxy-5-norbornene-2,3-dicarboxylic acid imide [21715-90-2] M 179.2, m 165-166", 166-169", pKesi-6 Dissolve in CHCI3, filter, evaporate and recrystallise from EtOAc. IR (nujol) 1695, 1710 and 1770 (C=0), and 3100 (OH) cm. 0-Acetyl derivative has m 113-114° (from EtOH) with IR bands at 1730, 1770 and 1815 cm only, and the 0-benzoyl derivative has m 143-144° (from propan-2-ol or C6H6). [Bauer and Miarka J Org Chem 24 1293 1959 Fujino et al. Chem Pharm Bull Jpn 22 1857 1974],... 

Dicarbonsaure-imide ergeben als cyclische sekundare Carbonsaure-amide mit Hydri-den die verschiedensten Reduktionsprodukte, z. B. Hydroxy-lactame, Lactame, cyclische Amine, a>-Hydroxy-carbonsaureamide und a>-Amino-alkohole4. 

C13H17NO 63367-12-4) see Ibuprofen a-hydroxy-a-methyl-4-(2-methylpropyl)benzeneethan-imidic acid methyl ester hydrochloride... 

FIGURE 8.3 Synthesis of amides by aminolysis of unisolated activated esters obtained using carbodiimide by (A) ammonium hydroxide,12 (B) diaminomethane dihydrochloride neutralized with Et3N,15 and (C) the amine of crystalline salts of additives, R = H, Me, Et.13 DCC = dicyclohexylcarbodiimide HOBt = 1-hydroxybenzotriazole HONSu = A-hydroxysuccin-imide HONp = p-nitrophcnol HODhbt = 3-hydroxy-4-oxo-3,4-dihydrobenzotriazine. 

Azole A-oxides, A-imides and A-ylides are formally betaines derived from A-hydroxy-, A-amino-and A-alkyl-azolium compounds. Whereas A-oxides (Section 3.4.3.12.7) are usually stable as such, in most cases the A-imides (Section 3.4.3.12.5) and A-ylides (Section 3.4.3.12.3) are found as salts, which deprotonate readily only if the exocyclic nitrogen or carbon atom carries strongly electron-withdrawing groups. 

Other preparations of 2-iminothiazolidin-4-ones which are discussed in the review by Brown139 utilize the reactions of thiourea with a-hydroxy acids,146 ethyl diazoacetate,73 glycidic esters,74,147 cinnamic acid,148 unsaturated diacids (fumaric, maleic, and citraconic) or their esters or imides,149-152 and propiolic esters.153,154 There has been considerable controversy in the literature surrounding the propiolic ester synthesis since many workers have proposed that the products are 1,3-thiazines (see Section IV, B, 1). The pertinent papers in this controversy have been summarized by Cain and Warrener.155 Nagase158 has recently settled the argument in favor of the 2-iminothiazolidin-4-... 

Asymmetric hydroxylation of chiral imides The (Z)-spdium enolates of the chiral imides 2 and 3 undergo asymmetric hydroxylation on reaction with 2-(phen-ylsulfonyl)-3-phenyloxaziridine (1). The products [(R)-4 and (S)-6] are solvo-lyzed to (R)- and (S)-a-hydroxy esters. This hydroxylation can also be effected with MoOPh, which is much less reactive than 1 but slightly more stereoselective. In general 1 is preferred to MoOPh because of the higher yields. 

Similar to the ring enlargement of a cyclic imide to give 1,6- and 1,7-naphthyridines (see Section III,B) the imide 97 is reported123 to undergo ring enlargement to form the hydroxy ester (98). 

The application of antibiotics as chiral selectors has resulted in the successful resolution of almost all types of neutral, acidic, and basic racemic molecule. These antibiotics have been used for the enantiomeric resolution of amino acids, their derivatives, peptides, alcohols, and other pharmaceuticals. The selectivities of the most commonly used antibiotic-based (vancomycin, teicoplanin, and ristocetin A) CSPs varied from one racemate to another and are given in Table 1. Vancomycin was used for the chiral resolution of amino acids, amines, amides, imides, cyclic amines, amino alcohols, hydantoins, barbiturates, oxazolidinones, acids, profens, and other pharmaceuticals. Teicoplanin was found to be excellent chiral selector for the enantiomeric resolution of amino acids, amino alcohols, imides, peptides, hydantoins, a-hydroxy and halo acids, and oxazolidinones, whereas ristocetin A is capable of chiral resolution of amino acids, imides, amino... 

Reversed phase Amines, amides, imides, acids, profens a-Hydroxy acids, oxazolidinones, amino acids, peptides a-Hydroxy acids, acids, profens, amino acids, amino esters, hydantoins, peptides... 

Analytical Properties Substrate has 38 chiral centers and 7 aromatic rings surrounding 4 cavities (A, B, C, D), making this the most structurally complex of the macrocyclic glycopeptides substrate has a relative molecular mass of 2066 this phase can be used in normal, reverse, and polar organic phase separations selective for anionic chiral species with polar organic mobile phases, it can be used for a-hydroxy acids, profens, and N-blocked amino acids in normal phase mode, it can be used for imides, hydantoins, and N-blocked amino acids in reverse phase, it can be used for a-hydroxy and halogenated acids, substituted aliphatic acids, profens, N-blocked amino acids, hydantoins, and peptides Reference 47, 48... 

DA Evans, MM Morrissey, RL Dorow. Asymmetric oxidation of chiral imide eno-lates. A general approach to the synthesis of enantiomerically pure a-hydroxy carboxylic acids. J Am Chem Soc 107 4346-4348, 1985. 

US 5,028,681 (American) 1991 Novel poly(imide siloxane) block copolymers and process for their preparation General Electric EN Peters Injection moldable block copolymers with high IV and excellent chemical/physical properties. Blends useful for impact modification Novel siloxane-imide block copolymers and a process for their preparation are covered. The method involves reacting a hydroxy-terminated polyimide oligomer with a siloxane oligomer with dimethylamino, acetyl or chlorine end-groups... 

Trifluoropropcnc itself reacts regioselectively with various nitrile oxides, even nonaromatic nitrile oxides. The latter arc prepared in one step from oximes and A -chlorosuccin-imide, or in a two-step sequence with isolation of the hydroximoyl chlorides. Cycloadducts, obtained at room temperature in the presence of triethylamine, are then converted into trilluoro- 8-hydroxy ketones 9 by reductive cleavage. The reaction with a dipole substituted by a group derived from L-phcnylalanine allows the preparation of chiral ketones. ... 

Yet a further reaction which forms three bonds is the use of imidic esters with suitably functionalized ketones (e.g. a-hydroxy, a-bromo). This method is exemplified by the synthesis of a new imidazole alkaloid (146), which had been isolated from a member of the Urticaceae family (80AHC(27)24l), and by the more general synthesis of 4-alkyl-5-methoxymethylimidazole (147) (79AP107). The cyclization process, which takes place in liquid ammonia, may be complicated by 2-alkylbutanamide by-products which result from Favorskii rearrangement of the bromomethoxy ketones (Scheme 83). 

Reduction of one carbonyl group to a hydroxy group in cyclic imides has been achieved to afford useful synthetic intermediates. The reaction (Scheme 17) is analogous to that shown for lactams (Scheme 16). Thus, reduction of cyclic imides (36) with NaBH4 in acidulated water has given good yields of the hydroxy lactam (37).Many similar examples by the same research group have appeared.With so-... 

Thiazole A -oxides, A -imides, and A -ylides are formally betaines derived from A -hydroxy-, A -amino-, and A -alkyl-azolium compounds. Where the cation is involved, reactivity is similar to that of thiazolium ions. 

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