- FeCl3·6H2O/acetaldehyde, a versatile system for the deprotection of ketals and acetals via a transacetalization process
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Mild and efficient catalytic deprotection of ketals/acetals mediated by FeCl3·6H2O/acetaldehyde has been described in this paper. The versatility and high chemoselectivity of the iron(iii)/aldehyde system are demonstrated by a large scope of examples. Deprotected ketones/aldehydes are nearly quantitatively isolated after filtration over a pad of silica gel followed by evaporation of volatile by-products.
- Schiavo, Lucie,Jeanmart, Lo?c,Lanners, Steve,Choppin, Sabine,Hanquet, Gilles
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p. 1421 - 1424
(2017/02/23)
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- ETHER DERIVATIVES OF BICYCLIC HETEROARYLS
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The invention relates to compounds of formula (I), wherein the substituents are as defined in the specification; to processes for the preparation of such compounds; pharmaceutical compositions comprising such compounds; such compounds as a medicament; such compounds for the treatment of a proliferative disease
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Page/Page column 91
(2011/04/18)
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- Indium(III) trifluoromethanesulfonate as an efficient catalyst for the deprotection of acetals and ketals
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(Chemical Equation Presented) Acetals and ketals are readily deprotected under neutral conditions in the presence of acetone and catalytic amounts of indium(III) trifluoromethanesulfonate (0.8 mol %) at room temperature or mild microwave heating conditions to give the corresponding aldehydes and ketones in good to excellent yields.
- Gregg, Brian T.,Golden, Kathryn C.,Quinn, John F.
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p. 5890 - 5893
(2008/02/09)
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- Intramolecular Cyclization of 4-[3-(Trimethylsilyl)prop-1-en-1-yI]-cyclohexanecarbaldehyde with Loss of Formyl Carbon
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Treatment of cis- and trans-4-[3-(trimethylsilyl)prop-1-en-1-yl]cydohexanecarbaldehyde (2a and 2b) with tetrabutylammonium fluoride in dilute tetrahydrofuran afforded 7-vinylbicyclo(2.2.1]heptan-1-ol (3), the same product obtained from 4-[3-(trimethylsilyl)prop-1-en-1-yl]cyclohexanone (1). It was found that oxidative deformyhition of 2a, b to 1 takes place under basic conditions before the cyclization to 3. It was also shown that cyclization of allylsilane with carbonyl does not proceed via an eclipsed conformation.
- Kuroda, Chiaki,Murase, Atsushi,Suzuki, Hideyuki,Endo, Toru,Anzai, Shuzo
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p. 1639 - 1647
(2007/10/03)
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- Enzymatic Preparation of Chiral 4-Hydroxy-2,2-dimethyl-1-cyclohexanone as a Chiral Building Block
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(S)-4-Hydroxy-2,2-dimethyl-1-cyclohexanone (1a) was prepared by two enzymatic methods. 1,4-Cyclohexanediol was converted to monoacetal (11) via (+/-)-1a.Enzymatic reduction of 11 by baker's yeast gave (S)-1 of almost 100 percent e.e.Direct hydroxylation of 2,2-dimethyl-1-cyclohexanone (14) by P-450 camphor monooxygenase of the cloned genes of Pseudomonas putida PpG1 gave (S)-1a of almost 100 percent e.e., too.According to Mitsunobu's method, SN-2 inversion of (S)-1 gave (R)-1.
- Yamamoto, Hiroshi,Oritani, Takayuki,Koga, Hideo,Horiuchi, Tadao,Yamashita, Kyohei
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p. 1915 - 1921
(2007/10/02)
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- Syntheses and biological activities of (+/-)-streptovitacin A and E-73.
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(+/-)-Streptovitacin A (1) and its stereoisomers were synthesized by an aldol reaction of (+/-)-2,4-dimethyl-4-trimethylsiloxy-1-cyclohexanones (4b and 9) with 4-(2-oxoethyl)-2,6-piperidinedione (5). E-72 (2) was derived from synthetic 1. (+/-)-1 showed m
- Kondo,Oritani,Yamashita
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p. 1531 - 1536
(2007/10/02)
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- Simple and Chemoselective Deprotection of Acetals Using Aqueous Dimethyl Sulfoxide
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Deprotection of acetals was achieved in aqueous dimethyl sulfoxide under neutral reaction condition.Selective cleavage of acyclic acetals bearing various types of acid labile protecting groups was also reported.
- Kametani, Tetsuji,Kondoh, Hirotsune,Honda, Toshio,Ishizone, Hiroyuki,Suzuki, Yukio,Mori, Wakako
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p. 901 - 904
(2007/10/02)
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- 1-Methyl-1-cyclohexyl Cations. Equilibria in Search of Structures
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Solutions of the 1-methyl-1-cyclohexyl cation 1, by four independent criteria, show unequivocal evidence for a populated equilibrium involving two different "structures" of this cation.One of these criteria makes use of a remarkably large new equilibrium isotope effect, a method that should have general structural use in other carbocation systems.Unfortunately, our previous assignment of a chair and twist-boat conformation for the structures dose not accord with the new data.From an analysis of the 13C and 1H NMR shifts and KH/KD isotope effects for 1 and a series of ring-methylated analogues, it can be deduced that both structures are chair conformers and that one structure must involve extensive α-C-H hyperconjugation, while the other structure involves predominantly C-C hyperconjugation.The very existence of this type of isomerism in observable carbocations is unprecedented and has important implications for the field in general.
- Kirchen, R. P.,Ranganayakulu, K.,Sorensen, T. S.
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p. 7811 - 7816
(2007/10/02)
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- Synthesis of (+/-)-Mesembranol and (+/-)-O-Methyljoubertiamine. Aza-Ring Expansion of cis-Bicyclooctanones
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The Syntheses of (+/-)-mesembranol (1) and (+/-)-O-methyljoubertiamine (2) are described.Each synthesis is developed from a regio- and stereospecific heteroannelation sequence of the respective 1-arylcyclohexanes 4 and 10 to provide the 3a-aryl-cis-octahy
- Jeffs, Peter W.,Cortese, Nicholas A.,Wolfram, Joachim
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p. 3881 - 3886
(2007/10/02)
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- 4'-Fluoro-4-{[4-(phenyl)cyclohexyl]amino}butyrophenones and the salts thereof
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This invention relates to novel 4-phenylcyclohexylamines embraced by the formula SPC1 Wherein ? is a generic expression denoting cis and trans stereoconfiguration and mixtures thereof; R is selected from the group consisting of alkyl of from one through four carbon atoms, fluorine, chlorine, bromine, trifluoromethyl, nitro and alkoxy of from one through four carbon atoms; R' and R1 are selected from the group consisting of hydrogen and alkyl of from one through four carbon atoms; R2 is selected from the group consisting of hydrogen, alkyl of from one through four carbon atoms, alkanoyl of from one through three carbon atoms, alkylsulfonyl of from one through three carbon atoms, arylsulfonyl of from six through ten carbon atoms, alkylcarbamoyl wherein alkyl is from one through four carbon atoms, alkoxycarbonyl wherein alkyl is from one through four carbon atoms, ring monosubstituted aroylalkyl wherein the substituents have the same meaning as R, above, aryl is from six through ten carbon atoms and alkyl is from one through six carbon atoms and bis (ring monosubstituted) arylalkyl wherein the substituents have the same meaning as R, above, aryl is from six through ten carbon atoms and alkyl is from one through six carbon atoms; R1 and R2 when taken together with --N is a saturated heterocyclic amino radical selected from the group consisting of unsubstituted and monosubstituted pyrrolidino, piperidino, hexamethylenimino, morpholino and piperazino; and an acid addition salt thereof. It also relates to intermediates and processes for the preparation of the aforesaid novel compounds (1) and novel derivatives thereof. The systemic administration to humans and animals of the novel compounds (1) depresses their central nervous systems.
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