Synthesis of monocyclic nine-membered compounds by the [4+3+2] cycloaddition-bond cleavage strategy

N–O linkage in carbohydrates and glycoconjugates

“…Substituted hydroxylamines can be prepared either from commercially available hydroxylamine derivatives through N-or O-derivatization, or from acylated hydroxylamines, oxime, or other nitrogen-containing compounds. N-Derivatization of hydroxylamines (Scheme 1) has been achieved by (a) nucleophilic substitution of highly nucleophilic hydroxylamine derivatives with a variety of primary and secondary alkylating agents; 51,52 (b) Mitsunobu reaction with alcohol; 51 (c) ringopening of epoxide by O-protected hydroxylamine; 51,53,54 (d) inter-or intramolecular 1,4-addition of hydroxylamines as well as N-or O-alkylhydroxylamines to activated carbon-carbon double bonds; 51,55 (e) intramolecular nucleophilic addition of hydroxylamine or hydroxamic acids to unactivated CvC bonds under thermal 51 or oxidative conditions; 56 (f ) reaction of hydroxylamines as well as N-or O-alkylhydroxylamines with aldehydes followed by reduction (NaBH 3 CN/AcOH or HCl) [57][58][59] or by carbon, oxygen, nitrogen or phosphorous nucleophile addition to oxyiminium intermediates; 51 (g) Pd(0)-catalysed three-component cascade reactions of allene and halides or triflates with protected hydroxylamines. 60 O-Derivatization of hydroxylamines (Scheme 2) is usually performed through (a) Mitsunobu reaction between alcohol and PhthNOH; [61][62][63] (b) nucleophilic substitution of bromide, 12,14,[64][65][66] iodide, 67 α-bromoesters [68][69][70] tosylate, 71 or mesylate 57,72,73 by PhthNOH, BocNHOH, BocB(Me)OH, BzNHOH, CF 3 CONHOH; (c) reaction of tertiary alcohol with stoichiometric BF 3 •Et 2 O and PhthNOH; 74 (d) alkoxide amination with 3,3′-di-tert-butyloxaziridine 75 or 3-trichloromethyloxaziridine; 76 and (e) Cu(I)/PhI(OAc) 2 -catalyzed 1,2-dihydroxylamination of alkenes.…”

“…119 Phthaloyl, tert-butoxycarbonyl, benzyloxycarbonyl, 2-chlorobenzyloxycarbonyl, ethoxyethylidene, diphenyl-p-tolylmethyl, trifluoroacetyl 120 or 4,5dimethoxy-2-nitrobenzyl groups have been employed for the protection of oxyamine. The phthaloyl group can be removed by (methyl)hydrazine, 62,73 methylamine, 52,121 NH 3 122 or NaBH 4 , 12,65 HCl/AcOH 29,31 while benzyl carbamate can be removed by hydrogenolysis, 62,109 tert-butoxycarbonyl, 33,70 ethoxyethylidene, 115,116 diphenyl-p-tolylmethyl 73 and 2-chlorobenzyloxycarbonyl 66 groups under acidic conditions. It is to be noticed that partial reduction of the phthalimidooxyl group by NaBH 4 123 and its ring-opening under Zemplén conditions 124 have been observed.…”

Progress in the Synthesis and Transformations of Alkylidenecyclopropanes and Alkylidenecyclobutanes

“…A succeeding extension considered a hydroxylamine moiety in the spacer, as a method for providing functionalized cyclononane derivatives in view of the easily cleavable N–O bond. Dienynyl hydroxylamines 960 reacted with ACP 347 under the usual conditions in the presence of catalytic Ni­(cod) 2 and PPh 3 to afford cyclononadiene-fused oxazines 961 in poor yield for the case of 961b but satisfactory for 961a (Scheme ) . This latter compound gave the aminoalcohol 962 on reductive cleavage of the N–O bond with Mo­(CO) 6 , while reaction with SmI 2 unexpectedly generated the homoallylhydroxylamine 963 .…”

Enantioselective synthesis of 3-substituted 1,2-oxazinanes via organocatalytic intramolecular aza-Michael addition

“…For example, the chiral 1,2-oxazinane 2a could be reduced by Mo(CO) 6 to the corresponding chiral 1,4-amino alcohol 4a in 79% yield without affecting the stereochemistry and optical purity (Scheme 2). 11 Our method presented here provides a powerful route to chiral 1,4-amino alcohols, which are potential chiral building blocks for the synthesis of biologically active molecules. 12 In order to account for the stereochemical outcome of this reaction, a mechanistic rationale was proposed (Fig.…”