181136-52-7

Upstream product

• 546-68-9 titanium(IV)isopropoxide 
• 85-43-8 1,2,3,6-Tetrahydrophthalic anhydride 
• 67-63-0 isopropyl alcohol 
• 935-79-5 cis-1,2,3,6-tetrahydrophthalic anhydride 

Downstream Products

• 130931-83-8 (1S,4R)-2-azabicyclo[2,2,1]hept-5-en-3-one 

Relevant academic research and scientific papers

Desymmetrization of acid anhydride with asymmetric esterification catalyzed by chiral phosphoric acid

Asymmetric desymmetrization of σ-symmetric acid anhydrides was achieved with chiral phosphoric acid as a Br?nsted acid catalyst. The key of success was finding of benzhydrol and 2,2-diphenylethanol as the nucleophiles of choice. The corresponding half esters were obtained in good yields with high selectivity.

Reversible Switching and Recycling of Adaptable Organic Microgel Catalysts (Microgelzymes) for Asymmetric Organocatalytic Desymmetrization

Adaptable enzyme-mimetic catalysts based on temperature-responsive polymer microgels (microgelzymes) have been developed. By a simple change in the temperature, a microgel catalyst can be reversibly switched into its soluble or precipitated form, thus com

Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

A family of novel chloramphenicol base-amide organocatalysts possessing a NH functionality at C-1 position as monodentate hydrogen bond donor were developed and evaluated for enantioselective organocatalytic alcoholysis of meso-cyclic anhydrides. These structural diversified organocatalysts were found to induce high enantioselectivity in alcoholysis of anhydrides and was successfully applied to the asymmetric synthesis of (S)-GABOB.

146. Polymer- and dendrimer-bound Ti-TADDO lates in catalytic (and stoichiometric) enantioselective reactions: Are pentacoordinate cationic Ti complexes the catalytically active species?

α,α,α′,α′-Tetraaryl-1,3-dioxolane-4,5- dimethanols (TADDOLs), containing styryl groups either at C(2) of the heterocyclic ring or in the α-position, were prepared in the usual way (18-22, 24, 25). These compounds were copolymerized with styrene and divinylbenzene in a suspension, yielding polymers (33-40, Scheme 3) as beads with a rather uniform particle-size distribution (150-450 μm), swellable in common organic solvents, HOCH2- and BrCH2-substituted TADDOLs were also prepared and used for attachement to Merrifield resin or to dendritic molecules (23, 26-32). The TADDOL moieties in these materials are accessible to form Ti (and Al) complexes (Scheme 4) which can be used as polymer- or dendrimer-bound reagents (stoichiometric) or Lewis acids (catalytic). The reactions studied with these new chiral auxiliaries are: enantioselective nucleophilic additions to aldehydes (of R2Zn and RTi(OCHMe2)3; Schemes, Table 1) and to ketones (of LiAlH4, Table 2); enantioselective ring opening of meso-anhydrides (Scheme 6); [4+2] and [3+2] cycloadditions of 3-crotonyl-1,3-oxazolidin-2-one to cyclopentadiene and to (Z)-N-benzylidenephenylamine N-oxide (→ 48, 9, Scheme 7, Tables 3, , and Fig. ). The enantioselectivities reached with most of the polymer-bound or dendritic TADDOL ligands were comparable or identical to those observed with the soluble analogs. The activity of the polymer-bound Lewis acids was only slightly reduced as compared with that encountered under homogeneous conditions. Multiple use of the beads (up to 10 times), without decreased performance, has been demonstrated (Figs. 3 and 4). The poorer selectivity in the Diets-Alder reaction (Scheme 7a), induced by the polymer-bound Cl2Ti-TADDOLate as compared to the soluble one, is taken as an opportunity to discuss the mechanism of this Lewis-acid catalysis, and to propose a cationic, trigonal-bi-pyramidal complex as the catalytically active species (Fig. 6) It is suggested that similar cations may be involved in other Ti-TADDOLate-mediated reactions as well.