Phosphoric chiral cyclic

Our group has synthesized chiral cyclic phosphoric acid diesters (41), derived from (P)-BINOL, and studied their catalytic activity in the Mannich-type reaction of ketenesilylacetal with aldimines (Scheme 2.83). Although (41a) was not effective as... 

Ten Hoeve W, Wynberg H (1985) The design of resolving agents. Chiral cyclic phosphoric... 

In 1993, Alexakis et al. reported the first copper-catalyzed asymmetric conjugate addition of diethylzinc to 2-cyclohexenone using phosphorous ligand 28 (32% ee).36 An important breakthrough was achieved by Feringa et al. with chiral phosphoramidite (S,R,R)-29 (Figure 1), which showed excellent selectivity (over 98% ee) for the addition of 2-cyclohexenone.37 Since then, efficient protocols for the conversion of both cyclic and acyclic enones, as well as lactones and nitroalkenes, have been developed featuring excellent stereocontrol. 

Computational methods are increasingly being brought to bear on the crystallographic aspects of chiral crystals. The possibility that one could predict the crystal structures of a particular diastereomeric salt pair with an error in calculated lattice energy of less than 4 kcal/mole has been demonstrated for the system formed by a chlorine-substituted cyclic phosphoric acid and ephedrine [64]. In another study, it was demonstrated that the stability difference of the diastereomeric salt pairs of... 

Simultaneously and independently, Cullis and Lowe developed a second general methodology for the synthesis of, 0, 0-labeled chiral phosphate monoesters (76, 77). This synthesis relies upon the synthesis of a cyclic hydrobenzoin triester of the alcohol or phosphoric acid followed by hydrogenolysis to liberate the isotopically labeled monoester product (Fig. 2). Hydrobenzoin, chiral by virtue of stereospecific labeling with 0 and 0, is the source of the two specified oxygen isotopes, and O is derived from H2 0 via P OCL. The reader is referred to the articles by Cullis and Lowe for details of the synthesis. 

Cyclic derivatives of phosphoric acid with chiral amino alcohols, e.g., 71, have been used as chiral electrophilic animation reagents (Section D.7.I.). As an example of such a compound, the reaction of (—)-ephedrine with phosphoryl chloride is given. 

Bases N-protected amino acids Tartaric acid and derivatives (dibenzoyl- and di-p-toluyltartaric acids) Mandelic acid and derivatives (O-acetylmandelic acid and O-methylmandelic acid) l,l -Binapthylphosphoric acid Camphorsulfonic acid Deoxycholic acid Cyclic phosphoric acid Others (malic acid, lactic acid and derivatives, Mosher s acid, N-derivatized amino acids, etc.) The same reagents as for acids (brucine, quinine, ephedrine, pseudoephedrine and synthetic chiral bases) [32-35] [36-38] [39-40] [41] [42] [29] [43-45]... 

There is also one example in which a chiral phosphoric acid has been employed as catalyst in the reaction. In particular, the addition of several cyclic p-ketoesters to methyl vinyl ketone was found to occur smoothly in the presence of several chiral phosphoric acids (Scheme 4.35). As mentioned earlier, a key feature of the chiral phosphoric acid catalyst is the backbone binaphthyl axial chirality together with the incorporation of bulky substituents at the 2 positions. In this case, 60b was identified as an appropriate promoter of the reaction leading to the corresponding Michael adducts in excellent yields, although with moderate enantioselectivity. In addition, the authors succeeded in applying this reaction to a procedure to carry out a subsequent Robinson-type annulation. 

A chiral phosphoric acid-catalyzed Petasis-Ferrier-type rearrangement of a seven-membered cyclic vinyl acetal resulted in the formation of a chiral tetrahydrofuran species. It was found that nonclassical hydrogen bonds between the catalyst and the substrate play an important role in controlling the stereoselectivity (14CS3515). 

More recently. List and co-workers [169], have reported the asymmetric epox-idation of cyclic enones, using a chiral primary diamine (111) and a phosphoric acid derived from BINOL (112) (Scheme 12.29). With H2O2 as oxidant, the epoxides were obtained in good yields (63-82%) and moderate to good enantioselectivities (78-98%). They also tested amine 113, which provided better ee s (92 to 99%) and slightly lower yields (49-85% (Scheme 12.29). 

In 2010, Rueping s group reported the first enantioselective approach toward the synthesis of 4-substituted-4,5-dihydro-l//-[l,5]benzodiazepin-2(3//)-ones, which resemble cyclic (3-amino acids [65]. Due to the basic nature of these benzodiaze-pinones, the reactions conducted with various chiral phosphoric acid diesters gave only very low conversion, while improved reactivity was obtained when the corresponding Wtriflyl phosphoramides were employed as catalysts, with 2-naphthyl derivative selected as the best-performing one. Microwave irradiation proved to be beneficial to further improve the yields, and the reduction, followed by subsequent... 

Dihydrobenzodiazepine derivatives, which are generated from phenylene-diamine and substituted acetophenone, are racemized by the intramolecular retro-Mannich/Mannich process. Combination of this racemization with chiral phosphoric acid-catalysed transfer hydrogenation by Hantzsch ester gave cyclic 1,3-diamine having a quaternary stereogenic centre (Scheme 5.41) [114]. 

G. Dagousset, P. Retailleau, G. Masson, J. Zhu, Chem.-Eur. J. 2012, 18, 5869-5873. Chiral phosphoric acid-catalyzed enantioselective three-component Povarov reaction using cyclic enethioureas as dienophiles stereocontrolled access to enantio-enriched hexahydropyrroloquinolines. 

The catalytic asymmetric /-selective Diels-Alder annulation of a, -unsaturated /-butyrolactams with enones provided a synthesis of, y-functionalized bridged bi-or tri-cyclic dihydropyranopyrrolidin-2-ones in one step (up to 98% yield, >20 1 dr, and 99% ee) The inverse-electron-demand aza-Diels-Alder cycloaddition 0 of A-aryl-a,/0-unsaturated ketimines with enecarbamates in the presence of chiral bifunctional phosphoric acids produced 4,5,6-trisubstituted 1,4,5,6-tetrahydropyridines having three contiguous stereogenic centres in up to 84% yield, 95 5 dr, and 95% 5-Alkenylthiazoles react as in-out dienes with e-poor dienophiles in polar 44-2- 0 cycloaddition reactions. The cycloadditions are site selective. The mechanism is thought to lie between a concerted but highly asynchronous process and a stepwise process. 

In 2013, Gong et al. reported a relay catalytic domino hydroamination-redox reaction, which was able to directly assemble tertiary amine substituted 3-en-l-yne derivatives and anilines into the corresponding cyclic aminals by using a gold(i) complex and an achiral phosphoric acid." By using a chiral phosphoric acid, the authors have developed an enantioselective version of this reaction. As shown in Scheme 7.32, the reaction of l-(2-ethynylphenyl)pyrrolidine and p-anisidine in the presence of a catalytic combination of a chiral phosphoric acid and Ph3PAuNTf2 led to the... 

A relay catalytic hydroamination/redox reaction for the synthesis of cyclic aminals 83 from tertiary amine-substituted 3-en-l-yne derivatives 81 and various aniline derivatives 82 was recently developed by Gong and coworkers (Scheme 12.40) [43]. The gold carbene complex [(IPrlAuNTfj] and TfOH were found to be optimal cocatalysts for this cascade reaction. In their preliminary studies, the authors found that this reaction could be carried out in a highly enantioselective manner, despite that 2 equiv. of an expensive chiral phosphoric acid are required. Interestingly, the diastereoselectivity for a particular substrate appears to be independent of the catalyst or ee. This suggests that the enantioselectivity may result from the ring-closure step, rather than the hydride shift step. 

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