“…Isolated examples of the synthesis of α‘-hydroxy-β-alkoxy ketones from the double hydroxylation of β-alkoxy vinyl bromide, the oxidation of β-alkoxy trimethylsilyl enol ether, and other routes have been reported. α‘-Amino-β-alkoxy ketones were prepared from α‘-bromo-β-alkoxy ketones and α‘,β‘-epoxy-β-alkoxy ketones, but no general method has been published. The silyl enol ethers of acylsilanes [RCHC(SiMe 3 )OSiMe 3 ] were reacted effectively with acetals in the presence of BF 3 ·Et 2 O to give β-alkoxyacylsilanes; however, the starting material is difficult to prepare.…”
1-(α-Alkoxyalkyl)benzotriazoles
1a−d add to phenyl vinyl ether to form key
intermediates 4a−d,
which readily undergo lithiation and subsequent trapping by a variety
of electrophiles to give the
expected substituted derivatives 7a−d,
9a−c, 11, 13,
15, and 18 in high yields.
Subsequent
hydrolysis of these compounds provides a novel high-yield acyl anion
synthon approach for the
synthesis of β-alkoxy ketones 8 or α‘-functionalized
β-alkoxy ketones 10, 12, 14,
16, and 19 by
short procedures from readily available starting
materials.
“…Isolated examples of the synthesis of α‘-hydroxy-β-alkoxy ketones from the double hydroxylation of β-alkoxy vinyl bromide, the oxidation of β-alkoxy trimethylsilyl enol ether, and other routes have been reported. α‘-Amino-β-alkoxy ketones were prepared from α‘-bromo-β-alkoxy ketones and α‘,β‘-epoxy-β-alkoxy ketones, but no general method has been published. The silyl enol ethers of acylsilanes [RCHC(SiMe 3 )OSiMe 3 ] were reacted effectively with acetals in the presence of BF 3 ·Et 2 O to give β-alkoxyacylsilanes; however, the starting material is difficult to prepare.…”
1-(α-Alkoxyalkyl)benzotriazoles
1a−d add to phenyl vinyl ether to form key
intermediates 4a−d,
which readily undergo lithiation and subsequent trapping by a variety
of electrophiles to give the
expected substituted derivatives 7a−d,
9a−c, 11, 13,
15, and 18 in high yields.
Subsequent
hydrolysis of these compounds provides a novel high-yield acyl anion
synthon approach for the
synthesis of β-alkoxy ketones 8 or α‘-functionalized
β-alkoxy ketones 10, 12, 14,
16, and 19 by
short procedures from readily available starting
materials.
“…It was expected that the cyclization of α‘-amino-α,β-epoxyketones will not proceed so unambiguously, in view of the possibility of four- and five-membered ring formation, and also due to the smaller conformational flexibility (less number of conformations favorable for cyclization are formed) of the carbonyl substrate (Scheme ). The synthesis of functionalized azetidin-3-ones 78 , 80 was accomplished by cyclization of α‘-amino-α,β-epoxyketones 77 , 79 complexed with boron trifluoride, in aprotic polar solvents. ,− It was established that the heterocyclization proceeded stereospecifically, which was confirmed by transformation of both diastereomers with the erythro-configuration into the corresponding stereoisomeric 4-(arylmethoxymethyl)-2-hydroxymethyl-2-methyl-1-cyclohexylazetidin-3-ones. 23 …”
“…The mechanism of the formation of these compounds includes dissociation of the boron trifluoride complexes with recoordination of boron trifluoride from the nitrogen atom to the oxygen atom of the oxirane ring with subsequent intramolecular exo-attack of the amino group at the destabilized α-C−O bond of the oxonium complex. Formally, the process can be considered as an intramolecular nucleophilic substitution of the oxirane oxygen atom by the amino group …”
“…Alternatively, 2-benzylideneazetidin-3-ones 150 were obtained also from 4-(arylmethoxymethyl)-2-hydroxymethyl-2-methyl-1-cyclohexyl-azetidin-3-ones 148 by reaction with acetic anhydride (Scheme ) . Depending on the acetylation conditions, either the corresponding acetates 149 or 4-arylidene-2-acetoxymethyl-2-methyl-1-cyclohexylazetidin-3-ones 150 were produced 41 …”
Section: C2 Condensation Reactions − Synthesis Of
2-benzylideneazetid...mentioning
confidence: 99%
“…The synthesis of functionalized azetidin-3-ones 78, 80 was accomplished by cyclization of R′-amino-R,β-epoxyketones 77, 79 complexed with boron trifluoride, in aprotic polar solvents. 27,[86][87][88][89] It was established that the heterocyclization proceeded stereospecifically, which was confirmed by transformation of both diastereomers with the erythro-configuration into the corresponding stereoisomeric 4-(arylmethoxymethyl)-2-hydroxymethyl-2-methyl-1-cyclohexylazetidin-3ones.…”
I. Introduction 29 II. The Chemistry of Azetidin-3-ones 29 A. Structural Data 29 B. Synthetic Methods for Azetidin-3-ones 31 B.1. Carbonyl Group Generation in the Azetidine Ring 31 B.2. Intramolecular Cyclization Reactions 34 B.3. 1,3-Dipolar Cycloaddition Reactions 36 C. Chemical Properties of Azetidin-3-ones 37 C.1. Transformations of the Carbonyl Group 37 C.2. Condensation Reactions − Synthesis of 2-Benzylideneazetidin-3-ones 40 C.3. Ring Transformations of Azetidin-3-ones 40 C.4. Miscellaneous 41 III. The Chemistry of Oxetan-3-ones 42 A. Structural Data 42 B. Synthetic Methods for Oxetan-3-ones 43 B.1. Decomposition of Diazoketones 43 B.2. Oxidation Reactions 44 B.3. Intramolecular Displacement Reactions 46 B.4. Miscellaneous 47 C. Chemical Properties of Oxetan-3-ones 48 C.1. Ring Opening and Ring Expansion of Oxetan-3-ones 48 C.2. Transformations of the Carbonyl Group 49 IV. The Chemistry of Thietan-3-ones 50 A. Synthetic Methods for Thietan-3-ones 51 A.1. Synthesis from Acyclic Precursors 51 A.2. Synthesis by Ring Transformations 53 B. Chemical Properties of Thietan-3-ones 54 B.1. Transformations of the Carbonyl Group 55 B.2. Aldol Reactions 56 B.3. Ring Transformations 56 V. Acknowledgments 58 VI. References 58
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