- Diastereo- and Enantioselective Synthesis of (+)- and (-)-cis-2-Aminocyclobutanols
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The hitherto unknown (+)- and (-)-cis-2-aminocyclobutanols 6a,b and 7a,b, as well as the corresponding benzyloxycyclobutanamines 8a,b, have been synthesized by means of asymmetric reductive amination, with de values of 100percent and ee values ranging from 96.9 to 99.8percent. The relative cis configuration has been established by NO experiments, whereas the absolute stereochemistry has been deduced from the CD spectra of the corresponding salicylidene derivatives and confirms the like induction at C-1.
- Bisel, Philippe,Breitling, Elke,Frahm, August Wilhelm
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- [2,3]-Wittig Rearrangement as a Formal Asymmetric Alkylation of α-Branched Ketones
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The enantioselective [2,3]-Wittig rearrangement of cinnamyloxycyclopentanone derivatives was performed in the presence of a Cinchona-based primary amine. The described method provides synthetically valuable α-hydroxy ketones with quaternary stereogenic centers in excellent enantiomeric purities. Relying on the X-ray crystal structure of the product and the DFT calculations, we propose that the rearrangement is promoted by an intramolecular hydrogen bond between the substrate and the catalyst.
- Kimm, Mariliis,O?eka, Maksim,Kaabel, Sandra,Metsala, Andrus,J?rving, Ivar,Kanger, T?nis
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- Convenient Preparation of 'High-Surface Sodium' in Liquid Ammonia: Use in the Acyloin Reaction
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'Sodium on solid support' (5-20 wt.% of Na on NaCl, glass powder, poly(ethylene) and poly(propylene)) can be conveniently prepared via low-temperature (-33°C) deposition of sodium from its solution in liquid ammonia. Use of this reagent in the acyloin reaction of carboxylic esters gave the corresponding products in good yields.
- Makosza, Mieczyslaw,Grela, Karol
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- A convenient one-pot preparation of stable equivalents of cyclobutane-1,2-dione and cyclobutanetrione
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A very short, high-yielding, one-pot procedure has been developed for the preparation of half-protected cyclobutane-1,2-dione. This compound is much more stable than cyclobutane-1,2-dione itself and allowed further transformation to give diprotected cyclobutanetrione equivalents. Copyright Taylor & Francis Group, LLC.
- Deguest, Geoffrey,Bischoff, Laurent,Fruit, Corinne,Marsais, Francis
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- 1. 2 - double-trimethyl siloxy cyclobutene and its preparation process
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The invention belongs to the field of chemical material production, and especially relates to 1,2-bis(trimethylsilyloxy)cyclobutene, and a preparation method thereof. Preparation chemical equation of 1,2-bis(trimethylsilyloxy)cyclobutene is represented by a formula in the invention. According to the preparation method, existing of unreacted metallic sodium residue in a reaction mixture is indicated based on a phenomenon that a blue compound is obtained via reaction of benzophenone with metallic sodium in an anhydrous solution; and a convenient and feasible method used for determining metallic sodium residual after reaction is provided, and potential safety hazards in post treatment processes are avoided completely.
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Paragraph 0023; 0024; 0025; 0026; 0027; 0028-0044
(2017/10/07)
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- Convenient preparation of metals deposited on solid supports and their use in organic synthesis
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'High-surface alkali metals' can be conveniently prepared via deposition of corresponding metals on various supports such as sodium chloride, polyethylene, polypropylene and cross-linked polystyrene from their solutions in liquid ammonia. Alkali metals deposited on polymeric supports can be stored in form of stable suspensions in inert solvents and used for the acyloin and Dieckmann condensations and for preparation of organolithiums. Addition of the suspension of supported alkali metal to a solution of zinc chloride gave an active zinc on polymeric support, which can be used for the Reformatski and Barbier reactions.
- Majkosza, Mieczyslaw,Nieczypor, Piotr,Grela, Karol
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p. 10827 - 10836
(2007/10/03)
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- Stereochemical studies of adrenergic drugs. Diastereomeric 2 amino 1 phenylcyclobutanols
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The synthesis of the cis and trans 2 amino 1 phenylcyclobutanols 2 and 3 is described. The results of the potentiation of the action of (-) norepinephrine by these two compounds are discussed.
- Miller,Hsu,Salman,Patil
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p. 180 - 184
(2007/10/06)
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