72936-48-2Relevant academic research and scientific papers
Sequential Reduction of Nitroalkanes Mediated by CS2 and Amidine/Guanidine Bases: A Controllable Nef Reaction
Ju, Minsoo,Guan, Weiyang,Schomaker, Jennifer M.,Harper, Kaid C.
, p. 8893 - 8898 (2019/11/11)
In this letter, we describe a mild, functional group-tolerant reductive Nef reaction that utilizes CS2 and an amidine or guanidine base to sequentially cleave N-O bonds. These conditions transform secondary nitroalkanes to ketones via an isolable oxime with minimal erosion at labile stereogenic carbons, show excellent compatibility with groups sensitive to oxidizing or reducing conditions, display good scalability, and are well-suited for generating useful 3-pyrrolidinone motifs from readily accessible 1,3-dipolar cycloaddition products.
Diastereoselective Synthesis of Nitroaldol Derivatives
Seebach, Dieter,Beck, Albert K.,Mukhopadhyay, Triptikumar,Thomas, Elizabeth
, p. 1101 - 1133 (2007/10/02)
Three methods are described by which diastereomerically enriched nitroaldols and their O-silylated derivatives can be prepared. threo-Nitroaldols prevail up to 10:1 over the erythro-isomers if doubly deprotonated nitroaldols 28 are quenched with acetic acid (THF/HMPT or DMPU, -100 deg C) (see Scheme 5 and Table 2).O-Trimethyl- or O-(t-butyl)dimethylsilylated (TBDMSi) erythro-nitroaldols can be obtained by protonation of the corresponding lithium nitronates (35, 39) in THF at low temperature (see Schemes 6 and 7).The erythro-O-TBDMSi-nitroaldol derivatives are also formed in the fluoride catalyzed addition of TBDMSi-nitronates (40-45) to aldehydes (see Schemes 8 and 9).In the latter reaction no 1,2-asymmetric induction is observed if α-branched silylnitronates or aldehydes are employed (see 48/49 and 50/51). - The stereochemical course of the reactions leading to erythro-O-TBDMSi-nitroaldols follows topological rules of broad applicability (see Scheme 10); possible mechanisms are discussed.- The configuration of erythro/threo-nitroaldols is determined by chemical correlation (see 24-26) and by 13C-NMR. spectroscopy. - Some examples of the preparation of diastereomerically enriched 1,2-aminoalcohols by reduction of the corresponding nitro compounds without loss of configurational purity are described (see Schemes 11 and 12).
3-Hydroxy-4-nitro-cyclohexanones from Ketones and 4-Nitrobutanoyl Chloride. A Ring Enlarging Five-Ring Annulation
Weller, Thomas,Seebach, Dieter,Davis, Raymond E.,Laird, Brian B.
, p. 736 - 760 (2007/10/02)
The 6-nitro-1,3-diketones 5, 8, 9, 10, and 11, prepared by a 1:1 acylation at the C-atom of non-hindered lithium enolates with 4-nitrobutanoyl chloride according to equation 3, are cyclized with sodium hydrogen carbonate in aqueous tetrahydrofuran to give the hydroxy-nitro-ketones 13-17.Such cyclic nitroaldols are not formed from the cyclopentanone, -heptanone, and -octanone, nor from the aryl derivatives 4, 6, 7 and 12, respectively.Except for the vicinally trisubstituted compound 14, the cyclization products are isolated in diastereomerically pure form.A crystal structure X-ray analysis reveals the trans-decalone and the cis-β-nitroalcohol configurations of the product 13 from cyclohexanone.Acetalization to 21-25 and catalytic hydrogenation of the nitro groups furnishes the amino alcohols 27-31 which are substrates for the Tiffeneau-Demjanow rearrangement.From the stereoelectronic control of this sextett rearrangement we deduce the configurations of the 1,4-diketones 35, 36, 39, 40, 43, 44, 46, and 47 formed under kinetic or thermodynamic conditions.The six-ring annulation with nitrobutanoic acid and the subsequent rearrangement are shown in Scheme 6; the sequence of reactions described here allows to carry out a ring enlargement of a cyclic ketone by one C-atom, with simultaneous annulation of a cyclopentanone ring.
