Tin Triflate Research Articles

ChemInform Abstract: Tin Triflate Promoted Synthesis of Bicyclic and Tricyclic Sulfonyl Dihydropyrans.

Abstract Tin triflate-promoted one-pot intramolecular annulation of α-geranyl or α-farnesyl β-ketosulfones 3–4 affords the respective bicyclic or tricyclic sulfonyl dihydropyrans 5–6 in moderate to good yields via a cascade cation-olefin-carbonyl carbocyclization process. The starting materials 3 and 4 were obtained by K2CO3-mediated α-geranylation or α-farnesylation of β-ketosulfones 1 with bromides 2a or 2b. The structures of the key products were confirmed by X-ray crystallography.

Tin triflate promoted synthesis of bicyclic and tricyclic sulfonyl dihydropyrans

Tin triflate-promoted one-pot intramolecular annulation of α-geranyl or α-farnesyl β-ketosulfones 3–4 affords the respective bicyclic or tricyclic sulfonyl dihydropyrans 5–6 in moderate to good yields via a cascade cation-olefin-carbonyl carbocyclization process. The starting materials 3 and 4 were obtained by K2CO3-mediated α-geranylation or α-farnesylation of β-ketosulfones 1 with bromides 2a or 2b. The structures of the key products were confirmed by X-ray crystallography.

Synthesis and application of tin triflate-containing MCM-41 as heterogeneous Lewis acid catalysts for the Mukaiyama aldol reaction at room temperature

Sn-containing MCM-41 (Sn-MCM-41) with different tin content was prepared by hydrothermal synthesis then treated with triflic acid to form tin triflate within the silica framework (SnOTf-MCM-41). XRD and UV–visible measurements revealed that SnOTf-MCM-41 have highly ordered mesoporous structures with tetrahedrally-coordinated Sn species. Moreover, results from FT-IR analysis revealed that triflate ligands are selectively coordinated with Sn4+ species in the mesoporous silica frameworks. SnOTf-MCM-41, as Lewis acid catalysts, promoted the Mukaiyama aldol reaction of benzaldehyde with 1-trimethylsiloxycyclohexene at room temperature and had greater catalytic activity than untreated Sn-MCM-41. Taking into account results from in situ FT-IR experiments using pyridine as probe molecule, the enhanced catalytic performance after triflic acid treatment was attributed to an increase in the number of acid sites, because of appearance of water tolerance by the formation of metal triflate species. In addition, the SnOTf-MCM-41 catalyst was reusable at least three times in the Mukaiyama aldol reaction.

ChemInform Abstract: Glycosyl 2-Pyridinecarboxylate as an Effective Glycosyl Donor: Glycosidation of Mannose, 2-Azidosugar, and 2-Deoxysugar into Disaccharides.

Glycosylation reactions using a glycosyl 2-pyridinecarboxylate as a glycosyl donor were performed. Glycosyl 2-pyridinecarboxylate was designed based on a variation of the Remote Activation Concept and is activated through bidentate coordination to mild Lewis acids such as copper triflate and tin triflate. This method was effective for the glycosidation of not only glucose, but several other sugars such as the mannose-type, 2-azidosugar-type, and 2-deoxysugar-type. Various disaccharides were obtained in excellent yield by this reaction.

Tin Triflate Catalyzed Selective Synthesis of N,N′‐Unsymmetrically Substituted N‐(Hydroxyclovanyl)‐N′‐aryl Acetamidines.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Tin Triflate Catalysed Selective Synthesis ofN,N′-Unsymmetrically SubstitutedN-(Hydroxyclovanyl)-N′-aryl Acetamidines

The unsymmetrically substituted amidines 6a-d have been prepared in one step from caryophyllene oxide (2), aromatic amines (4a-c, 5), and tin triflate as catalyst, in refluxing MeCN.

Highly Stereoselective Total Synthesis of Multiply Protected 3-Amino-3,6-dideoxyaldohexoses (Mycosamine/Mycaminose) by Aldol Condensation Reaction, Mediated by Tin Triflate, of Tricarbonyliron/α-Aminodienone Complexes

The divalent tin enol ether of the racemic complex between N-BOC-α-aminoheptadienone and tricarbonyliron reacts with both enantiomers of protected lactaldehydes to yield predominantly one optically active, easily isolable ketol diastereoisomer (45%). From the enantiomerically pure (S)-(+) complex and (R)-(+)-tert-butyldimethylsilyloxylactaldehyde, the major ketol is obtained almost exclusively (isolated yield 86%). From there, the multiply protected 3-amino-3,6-dideoxy-D-aldohexose mycosamine is obtained in a few high-yield steps (decomplexation, stereospecific reduction to an anti-1,3-diol, transformation into a diacetate and ozonolysis; absolute configurations S,S,S,R). Reduction of the ketol before decomplexation completely reverses the stereochemistry of the reaction [control by the Fe(CO)3 and not by the hydroxy group syn-diol], also giving access to the (R,S,S,R) series (configuration of the N,N-dimethylated mycaminose). The key structures were determined by X-ray diffraction.

Highly stereoselective synthesis of 3-amino-3,6-dideoxy-aldohexoses by tin triflate mediated aldol condensation reaction of tricarbonyl iron α-aminodienone complexes. Total synthesis of multiprotected mycosamine

The divalent tin enol ether of the racemic N-BOC α-aminodienone tricarbonyliron complex 4 reacts with both enantiomers of protected lactaldehydes to predominantly yield one optically active ketol diastereoisomer (45 %). From the enantiomerically pure complex (S)-(+)-4 and (R)-(+) tert butyldimethylsilyloxylactaldehyde this ketol is obtained almost alone (isolated 86 %). From there, the multi-protected 3-amino-3,6-dideoxy- d-aldohexose mycosamine is obtained in a few high yielding steps (decomplexation, stereospecific reduction to a 1,3-diol, transformation into a diacetate and ozonolysis; absolute configurations S,S,S,R). By reduction of the ketol before decomplexation, the stereochemistry of the reaction is completely reversed (control by the Fe(CO) 3 and not by the hydroxyl group), giving also access to the R,S,S,R series. (Structures determined by X-ray diffraction).

Glycosyl 2-Pyridinecarboxylate as an Effective Glycosyl Donor: Glycosidation of Mannose, 2-Azidosugar, and 2-Deoxysugar into Disaccharides.

Glycosylation reactions using a glycosyl 2-pyridinecarboxylate as a glycosyl donor were performed. Glycosyl 2-pyridinecarboxylate was designed based on a variation of the Remote Activation Concept and is activated through bidentate coordination to mild Lewis acids such as copper triflate and tin triflate. This method was effective for the glycosidation of not only glucose, but several other sugars such as the mannose-type, 2-azidosugar-type, and 2-deoxysugar-type. Various disaccharides were obtained in excellent yield by this reaction.

Mössbauer characterization of tin triflate Sn(OTf)2

151Sn Mossbauer spectroscopy was performed with tin triflate Sn(OTf)2 in order to determine its Mosbauer parameters for analytical purposes. The typical Mossbauer parameters at 80 K for crystalline Sn(OTf)2 are IS=4.01±0.02 mm/s and QS=1.20±0.04 mm/s and show that the stannous ion is at a site with less than cubic symmetry under perturbation of the crystal field effect.

ChemInform Abstract: Perfect Stereochemical Control in the Synthesis of syn‐α‐Methyl‐β‐hydroxy Thioesters by Asymmetric Aldol Reaction of Silyl Enol Ethers with Aldehydes.

AbstractCoupling of the aldehydes (I) with the ketene O,S‐acetal (II) in the presence of tin triflate, tributyltin fluoride, and a chiral diamine yields selectively the syn‐configurated β‐hydroxy thioloesters (III).

ChemInform Abstract: Synthesis of 1β‐Methylcarbapenem Key Intermediates Involving the Labile Acyl Auxiliary 4,4‐Dimethyl‐1,3‐oxazolidine‐2‐thione.

AbstractThe chiral amide (III), prepared by coupling of the azetidinone (I) with the tin triflate (II), reacts with the nucleophiles (IV) under substitution of the oxazolidinethione moiety, forming the carbapenem precursors (V).

ChemInform Abstract: Asymmetric Aldol Reaction of Silyl Enol Ethers with Aldehydes Promoted by the Combined Use of Chiral Diamine‐Coordinated Tin(II) Triflate and Tributyltin Fluoride.

AbstractThe aldehydes (I) are coupled with the O‐silyl ketene O,S‐acetales (II) in the presence of tin triflate, tributyltin fluoride, and a chiral pyrrolidinylmethylpiperidine to form the optically active β‐hydroxy thiolo esters (III).

ChemInform Abstract: A Novel Method for the Stereoselective Synthesis of β‐Aminoacid Derivatives via Tin(II) Carboxylic Thioester Enolates.

AbstractThe ketene (I) reacts with the tin mercaptide (II) to yield the thiolester enolate (III), which couples with the imines (IV) in the presence of tin triflate (V), giving the isomeric adducts (VI) and (VII).