Manuel Mancera

New derivatives of D-mannaric and galactaric acids. Synthesis of a new stereoregular Nylon 66 analog from carbohydrate-based monomers having the D-manno configuration

2,3,4,5-Tetra-O-methyl-D-mannaric and galactaric acids and their bis(pentachlorophenyl) esters have been prepared as crystalline compounds, in good yields, from D-mannitol and galactitol, respectively. A new stereoregular polyamide, analogous to Nylon 66, has been prepared by polycondensation of bis(pentachlorophenyl) 2,3,4,5-tetra-O-methyl-D-mannarate with 1,6-diamino-1,6-dideoxy-2,3,4,5-tetra-O-methyl-D-mannitol dihydrochloride. The polymer has a M(w) of 31,100 with a polydispersity of 1.5 (GPC). It was highly hygroscopic and soluble in ethanol, acetone, dimethyl sulfoxide, N,N-dimethylformamide and chloroform, but only slightly soluble in water.

Synthesis of d-mannitol and l-iditol derivatives as monomers for the preparation of new regioregular AABB-type polyamides

1,6-Diamino-1,6-dideoxy-2,3,4,5-tetra-O-methyl-D-mannitol (and its L-iditol analogue) suitable for their utilization as monomers in the preparation of linear polyamides are described. Regio- and stereoregular polyamides of the AABB-type have been prepared by the active ester polycondensation method from these C(2) symmetric monomers and suberic and dodecanedioic acids. The resulting polyamides were obtained in fair yields (70-60%) and were characterized by elemental analyses and infrared and 1H and 13C NMR spectroscopies. Their M(w) and M(w)/M(n) were determined by GPC relative to polystyrene standards. All of them were gummy non-crystalline solids.

Stereoselective 1,3-dipolar cycloadditions of nitrile oxides to sugar olefins. Synthesis of acyclic-sugar isoxazoline C-nucleoside analogs

Abstract The cycloaddition 1,3-dipolar of nitrile oxides to sugar nitro olefins and α,β-unsaturated carbonyl olefins has been investigated. The reaction is less regioselective that the cycloaddition of diazoalkanes to the same olefins and while nitrile oxides with bulky substituents afford the sterically less hindered cycloadducts, other nitrile oxides yield a mixture of the two possible regioisomers. However, the reactions seem to be highly stereoselective and single diastereomers were obtained in all the cases studied.

Synthesis of 3-(polyacetoxyalkyl)pyrroles from 3-aminocrotonic esters and open-chain sugar nitro-olefins

D-gluco- and D-galacto-3,4,5,6,7-Penta-acetoxy-1-nitrohept-1-ene (1 a and b) reacted with 3-(alkylamino)crotonic esters (2) yielding the Michael-type adducts (3) which have a preference for the intramolecularly bonded (Z)-configuration. These compounds were cyclized into 4-(D-gluco- or D-galacto-penta-acetoxypentyl)-1-alkyl-2-methylpyrrole-3-carboxylic esters (5), the O-deacetylation of which afforded the corresponding polyols (8). Periodate or lead tetra-acetate oxidation of (8) gave the pyrrole-3-carbaldehydes (9).

Stereoselective synthesis of pyrazoline derivatives by 1,3-dipolar cycloaddition of diazoalkanes to α,β-unsaturated carbonyl derivatives of sugars

New pyrazoline acyclonucleosides have been prepared by 1,3-dipolar cycloaddition reactions of diazoalkanes to derivatives of d-galacto-oct-2-enonate and d-galacto-non-3-enulose. The reactions were highly regio- and stereo-selective, and single isomers were obtained in good yields. A tautomeric equilibrium between the 1- and 2-pyrazoline structures was observed for some of the isomers in solution.

Reactions of sugar nitro-alkenes with acetoacetic esters

Abstract 3,4,5,6,7-Penta- O -acetyl-1,2-dideoxy-1-nitro- d - gluco -hept-1-enitol reacts with methyl acetoacetate in an unusual Michael reaction, giving the normal adduct ( 6 ), and a bicyclic derivative ( 9 ) that arises from quasi-dimerization of the former when a high concentration of the base is used. Acetylation of compound 9 gives the hydroxylamine O -acetate ( 10 ). From the reactions of 3,4,5,6,7-penta- O -acetyl-1,2-dideoxy-1-nitro- d - galacto -hept-1-enitol with ethyl and tert -butyl acetoacetate, the normal adducts ( 7 and 8 ) were isolated. The structures of compounds 6 to 10 were established on the basis of their spectral properties (u.v., i.r., mass, and 1 H- and 13 C-n.m.r.)

Reactions of sugar nitro-alkenes with 3-aminocrotonic esters

Abstract 3,4,5,6,7-Penta- O -acetyl-1,2-dideoxy-1-nitro- d - gluco - and - d - galacto -hept-1-enitol and 3,4,5,6-tetra- O -acetyl-1,2-dideoxy-1-nitro- d - xylo -hex-1-enitol react with 3-aminocrotonic esters, yielding mixtures of the epimeric Michael adducts. These are thermally stable, and do not cyclize to pyrroles. The structures, configurations, and conformations of these compounds were established on the basis of their spectroscopic and X-ray crystallographic data. The intramolecularly bonded, ( Z ) configuration was deduced for all of them. Mild hydrolysis of adducts with acid yields the corresponding 2-(nitromethylpolyacetoxyalkyl)acetoacetates.