Practical and Scalable Kinetic Resolution of BINOLs Mediated by a Chiral Counterion

BINOLs are valuable and widely used building blocks, chiral ligands, and catalysts that are effective across a remarkable range of different chemical transformations. Here we demonstrate that an ammonium salt catalyzed kinetic resolution of racemic BINOLs with benzyl tosylate proceeds with s up to 46. This is a scalable and practical process that can be applied across >30 different C₂‐ and non‐C₂‐symmetric BINOLs. Implementation of this method enables the enantioselective synthesis of a wide range of BINOL derivatives with over 99:1 e.r.     

Syntheses of manganese and iron tetraspirobifluorene porphyrins as new catalysts for oxidation of alkenes by hydrogen peroxide and iodosylbenzene

The condensation of pyrrole with 9,9′-spirobifluorene aldehyde yields new the 5,10,15,20-tetra(spirobifluorene) porphyrins; epoxidation of cyclooctene and styrene derivatives catalyzed by the manganese and iron complexes is reported using H₂O₂ and PhIO as oxygen atom donors.     

Synthesis of structurally diversified BINOLs and NOBINs via palladium-catalyzed C–H arylation with diazoquinones

Privileged biaryl frameworks, BINOL and NOBIN, were efficiently constructed with sole 1-DNQs as arylation reagents under one set of reaction conditions. The judicious selection of palladium-catalytic system plays a pivotal role in the excellent selectivities. This transformation accommodated fairly broad substrate generality for both 2-naphthol and N-Boc-2-naphthylamine and afforded the structurally diversified BINOLs and NOBIN derivatives in high efficiency. Notably, the bromosubstituents which cannot survive in conventional palladium-catalyzed reactions were well-compatible with this set of conditions, providing an effective handle for further enriching the library of BINOLs and NOBINs. Preliminary attempts on the asymmetric variant of this reaction were also performed with up to 80:20 er for BINOLs synthesis.     

Synthesis of chiral 3,3′-disubstituted 1,1′-binaphthyl-2,2′-disulfonic acids

A convenient synthesis of chiral 3,3′-disubstituted 1,1′-binaphthyl-2,2′-disulfonic acids (BINSA, 1) was developed. The key was directed ortho-lithiation of BINSA methyl ester 2 with n-BuLi and subsequent reaction with an electrophile. Electrophiles such as Br₂, I₂, Me₃SiOTf, and i-PrOB(Pin) reacted smoothly with 3,3′-dilithiated BINSA methyl ester, and the corresponding 3,3′-dihalo-, 3,3′-bis(trimethylsilyl)-, and 3,3′-diboryl-BINSA derivatives were obtained in yields of 21–78%. This simple synthetic method is highly attractive since the ability to prepare 3,3′-disubstituted BINOLs in advance can be useful.     

Lewis acid-catalyzed oxidative rearrangement of tertiary allylic alcohols mediated by TEMPO

Two methods for the oxidative rearrangement of tertiary allylic alcohols have been developed. Most of tertiary allylic alcohols studied were oxidized to their corresponding transposed carbonyl derivatives in excellent to fair yields by reaction with TEMPO in combination with PhIO and Bi(OTf)₃ or copper (II) chloride in the presence or not of oxygen. Other primary oxidants of TEMPO such as PhI(OAc)₂, mCPBA, and Oxone^® were unsatisfactory giving the enone in modest to low yields.     

Ru-Catalyzed Oxidations with Iodosylbenzene Derivatives. Substituent Effects on Selectivity in Oxidation of Sulfides and Alcohols

Oxidation of sulfides with PhIO/RuCl₂ (PPh₃)₃ leads to sulfones. Electronwithdrawing substituents in the aromatic ring of PhIO reduce the reactivity and improves selectivity of the system. Thus, with m-iodosylbenzoic acid sulfides are converted to sulfoxide. Under the same conditions aliphatic primary alcohols are transformed to aldehydes with m-iodosylbenzoic acid, while PhIO affords carboxylic acids.     

Synthesis of 3,3′‐Di(2‐Pyridyl)‐1,1′‐Bi‐2‐Naphthol Derivatives

Abstract

A new kind of (S)‐3,3′‐dipyridyl BINOLs (3a–d) with C ₂‐symmetry were synthesized in 79–84% yields by Suzuki coupling of the diboronic acid dipinacol ester (S)‐1 containing a (S)‐binaphthyl group with bromopyridine derivatives (2a–d) followed by hydrolysis.     

Iodine(III)-catalyzed benzylic oxidation by using the (PhIO)n/Al(NO3)3 system

Abstract

The first iodine(III)-based procedure for the benzylic oxidation of different arenes is described by using the (PhIO)_n/Al(NO₃)₃ system under catalytic conditions leading to the formation of the corresponding carbonyl derivatives. The method proceeds under mild, operationally simple, room temperature, short reaction times, and open flask conditions. In light of the organocatalysis relevance and the novelty of our protocol, we wish to communicate our initial results of this novel oxidation.     

A simple and highly effective method for hydrogenation of arenes by [Rh(COD)Cl]2

Hydrogenation of arenes, including chiral BINOLs and the lignin model compounds, has been achieved efficiently by using the simple complex [Rh(COD)Cl]₂ as catalyst precursor.     

Oxidative nitration of the amino group: synthesis of dinitramide and cyanonitramide salts

A convenient preparative method for the synthesis of potassium dinitramide and cyanonitramide salts was developed. The method involves reactions of nitramide or cyanamide with KNO₂ and PhI(OAc)₂ or PhIO in methanol.     

C,O‐Chelated BINOL/Gold(III) Complexes: Synthesis and Catalysis with Tunable Product Profiles

Unprecedented stable BINOL/gold(III) complexes, adopting a novel C,O‐chelation mode, were synthesized by a modular approach through combination of 1,1′‐binaphthalene‐2,2′‐diols (BINOLs) and cyclometalated gold(III) dichloride complexes [(C^N)AuCl₂]. X‐ray crystallographic analysis revealed that the bidentate BINOL ligands tautomerized and bonded to the Au^III atom through C,O‐chelation to form a five‐membered ring instead of the conventional O,O′‐chelation giving a seven‐membered ring. These gold(III) complexes catalyzed acetalization/cycloisomerization and carboalkoxylation of ortho ‐alkynylbenzaldehydes with trialkyl orthoformates.     

An iron catalyzed regioselective oxidation of terminal alkenes to aldehydes

Fe(BF(4))(2)·6H(2)O with pyridine-2,6-dicarboxylic acid and PhIO can efficiently catalyze the regioselective oxidation of terminal alkene derivatives to aldehydes under mild and benign reaction conditions.     

金属卟啉的合成及其对细胞色素P-450的模拟 12.μ-氧-双铁(Ⅲ) 卟啉系列化合物对环已烷的单充氧催化物作用

研究了九种μ-氧-双[四苯基卟吩合铁(Ⅲ)]衍生物[TXPPPe^Ⅲ]~O 在温和条件下PHIO环已烷氧化成环以醇和环已酮的反应,结果表明,该反应的产率和速率与卟啉环上取代基的特性常数之间存在的线性关系, 反应的产物分布和动力学性质与反应温度,溶剂型质以及空气有关,还考察了这一反应过程的另一竞争反应-氧化剂对[ TXPPEeⅢ[~O的破坏反应,根据文献报道和实验结果,本文对μ-氧-双铁(Ⅲ)卟啉催化环已烷羟基化反应的可能途径进行了探讨.     

Octopus Manganese Porphyrin with Polyglycol Chains as a Catalyst for the β-Selective Epoxidation of Cholesterol Derivatives

Synthesis of a novel octopus porphyrin with polyglycol chains 1a was achieved. The catalytic activity of 1a‘s manganese complex for the epoxidation of cholesterol derivatives with PhIO give a satisfactory conversion and regioselectivity.     

五氟代锰卟啉模拟酶体系快速混合停流吸收谱

采用快速混合停流技术,在实际反应条件下,考察了五氟代锰卟啉配合物Ｍｎ~Ⅲ（ＴＦＰＰ）Ｃ１与两种单氧给体亚碘酰苯ＰｈＩＯ和过氧苯甲酸ｍ－ＣＰＢＡ构建的细胞色素Ｐ－４５０模拟酶体系催化活性物种的生成及催化烯烃环氧化过程．在氧给体ＰｈＩＯ作用下,Ｍｎ~Ⅲ（ＴＦＰＰ）Ｃ１生成了高价锰氧卟啉配合物和双核μ－氧锰卟啉配合物,具有高的催化环氧化活性和催化剂稳定性．而在氧给体ｍ－ＣＰＢＡ作用下,Ｍｎ~Ⅲ（ＴＦＰＰ）Ｃ１则生成了一种较稳定物种,以致催化活性较低。     

Synthesis and activity of macrocyclized chiral Mn(III)-Schiff-base epoxidation catalysts

A series of chiral macrocyclic Mn(III)Salen complexes has been prepared with two salicylidene moieties linked in their 3 and 3′ positions by aliphatic polyether bridges of variable lengths or by a more rigid aromatic junction arm. X-ray structures of ligand precursors and of complex 8 have been performed. All complexes have been used in the asymmetric epoxidation of 1,2-dihydronaphthalene with NaOCl as oxygen atom donor and exhibited modest enantiomeric excesses. Complex 10 was selected to be tested with two cis-disubstituted olefins and several oxidants, namely NaOCl, PhIO and n-Bu₄NHSO₅. 2,2′-Dimethylchromene oxide was obtained from 2,2′-dimethylchromene with ee values of 56% and 74% when using 10 and NaOCl and PhIO, respectively.     

Immobilization of BINOL by cross-linking copolymerization of styryl derivatives with styrene, and applications in enantioselective Ti and Al Lewis acid mediated additions of Et2Zn and Me3SiCN to aldehydes and of diphenyl nitrone to enol ethers

The chiral ligand 1,1'-bi-2-naphthol (BINOL) has been succesfully immobilized on polystyrene. Several dendritic and non-dendritic BINOL derivatives (3, and 13-17), bearing at least two polymerizable styryl groups, were prepared and fully characterized. Suspension copolymerization of the MOM- or TIPS-protected cross-linking BINOL ligands (MOM = methyloxymethyl, TIPS = triisopropylsilyl) with styrene, cleavage of the protecting-groups, and loading with a Lewis-acid afforded catalytically active polystyrene-supported BINOLates. The polymer-bound BINOLs p-3, and p-13-p-16 were tested in the Ti-BINOLate-mediated addition of Et2Zn to PhCHO. The enantioselectivities (up to 93%) and conversions obtained with the polymer-bound catalysts were in most cases identical (within experimental error) to those obtained with the unsubstituted 1,1'-bi-2-naphthol and with the non-polymerized BINOL cross-linkers under homogeneous conditions. Special focus was put on the reusability of the supported catalyst: the polymer-beads were used in up to 20 consecutive catalytic runs, with the best polymers showing no or only minor loss of selectivity. BINOL-polymers p-17, obtained by copolymerization of a 3,3'-distyryl-substituted BINOL 17a with styrene, were used in the BINOL. AlMe-mediated cycloaddition of diphenyl nitrone with alkyl vinyl ethers. In all cases the exo/endo selectivity (> or =92:8) and the enantioselectivities with which the exo-cycloadducts were formed (> or =95%) correspond to those observed in the homogeneous reactions. A dendritically cross-linked BINOL-polymer was also employed in the Ti-BINOLate-mediated cyanosilylation of pivalaldehyde. The enantiopurity of the cyanohydrine obtained in the first run was as high as in the homogeneous reaction (72%); surprisingly the catalytic performance of the supported catalyst increased steadily during the first catalytic cycles to reach 83%. Thus, cross-linking BINOLs can be succesfully incorporated into a polystyrene matrix (without racemization!) to give polymer-bound BINOL ligands that give excellent performance over many catalytic cycles with catalytic activities comparable with those of soluble analogues.     

Synthesis of 7,7’-Disubstituted BINAP and Their Application in Asymmetric Catalytic Reaction

The design of new chiral ligands plays a very important role in the development of transition metal catalyzed asymmetric synthesis. Many chiral diphosphine ligands have been prepared and applied in asymmetric catalytic reactions with excellent enantioselectivities. Among the chiral diphosphine ligands reported, BINAP was found to have been the widest application in the transition metal catalyzed reaction. Recently we have developed a novel oxovanadium (Ⅳ) complex catalyst for the oxidative …     

Synthesis and properties of <Emphasis Type="Italic">N</Emphasis>-nitro-<Emphasis Type="Italic">O</Emphasis>-(4-nitrophenyl)hydroxylamine

Salts of N-nitro-O-(4-nitrophenyl)hydroxylamine were synthesized by a new method of oxidative nitration, involving the reaction of O-(4-nitrophenyl)hydroxylamine with KNO₂ or NaNO₂ in the presence of PhI(OAc)₂ or PhIO as oxidants. When using Na¹⁵NO₂, the samples containing the nitro group labeled with the ¹⁵N isotope were obtained. Acidification of the appropriate salt gave N-nitro-O-(4-nitrophenyl)hydroxylamine. It is the first N-nitrohydroxylamine isolated in the H-form. Its thermal stability was investigated and the probable mechanism of decomposition was suggested. From a comparison of the ¹⁴N and ¹⁵N NMR spectra of N-nitro-O-(4-nitrophenyl)hydroxylamine with those of its O- and N-methylated derivatives, its equilibrium with the aci-form (N=NOOH) was inferred.     

Chiral catalyst optimization using both solid-phase and liquid-phase methods in asymmetric aza Diels-Alder reactions

[formula: see text] In the presence of 1-5 mol % of a chiral zirconium catalyst, aza Diels-Alder reactions of aldimines with Danishefsky's dienes proceeded smoothly to afford the corresponding piperidine derivatives in high yields with high enantioselectivities. For the catalyst optimization, solid-phase and liquid-phase methods were successfully used. In the solid-phase approach, polymer-supported (R)-1,1'-binaphthols (BINOLs) have been synthesized and rapid optimization using the solid-phase reactions has been achieved. On the other hand, novel chiral zirconium cyanides were developed as excellent catalysts using the liquid-phase approach.