Rolando A. Spanevello

An efficient microwave-assisted green transformation of cellulose into levoglucosenone. Advantages of the use of an experimental design approach

The microwave-assisted pyrolysis of cellulose towards its conversion into levoglucosenone is reported. An experimental design approach was used to find the variables involved in this transformation. Using this approach we established the optimal conditions to obtain the maximum yield of product.

1,3-Dipolar cycloaddition reactions of azomethine ylides with a cellulose-derived chiral enone. A novel route for organocatalysts development.

Cellulose-derived chiral pyrrolidines were synthesized in excellent yields, regioselectivities, and stereoselectivities via a 1,3-dipolar cycloaddition reaction between levoglucosenone and azomethine ylides. An unprecedented isomerization event led to a new family of pyrrolidines with an unusual relative stereochemistry. Preliminary results showed that these compounds are promising organocatalysts for iminium ion-based asymmetric Diels-Alder reactions.

π-Stacking Effect on Levoglucosenone Derived Internal Chiral Auxiliaries. A Case of Complete Enantioselectivity Inversion on the Diels−Alder Reaction

Detailed quantum chemical calculations, experimental evidence, and NMR data rationalize the participation of pi-stacking interaction in the highly asymmetric Diels-Alder reaction using levoglucosenone derived internal chiral auxiliaries, including the appealing effect of inversion of the enantioselectivity by coordination of the substrate with Et 2AlCl.

Cellulose recycling as a source of raw chirality

Modern organic chemistry requires easily obtainable chiral building blocks that show high chemical versatility for their application in the synthesis of enantiopure compounds. Biomass has been demonstrated to be a widely available raw material that represents the only abundant source of renewable organic carbon. Through the pyrolitic conversion of cellulose or cellulose-containing materials it is possible to produce levoglucosenone, a highly functionalized chiral structure. This compound has been innovatively used as a template for the synthesis of key intermediates of biologically active products and for the preparation of chiral auxiliaries, catalysts, and organocatalysts for their application in asymmetric synthesis.

Joint Experimental, in Silico, and NMR Studies toward the Rational Design of Iminium-Based Organocatalyst Derived from Renewable Sources

An efficient organocatalyst for iminium-ion based asymmetric Diels-Alder (DA) reactions has been rationally designed. The most influential structure-activity relationships were determined experimentally, while DFT calculations and NMR studies provided further mechanistic insight. This knowledge guided an in silico screening of 62 different catalysts using an ONIOM(B3LYP/6-31G*:AM1) transition-state modeling, which showed good correlation between theory and experiment. The top-scored compound was easily synthesized from levoglucosenone, a biomass-derived chiral enone, and evaluated in the DA reaction between (E)-cinnamaldehyde and cyclopentadiene. In line with the computational finding, excellent results (up to 97% ee) were obtained. In addition, the catalyst could be easily recovered and reused with no loss in its catalytic activity.

Efficient enantiospecific entry to a highly functionalized cyclopentane building block

Abstract A simple and efficient route has been developed for the synthesis of a polyfunctionalized cyclopentane in enantiomerically pure form. D-Glucose is the source of chirality for this versatile building block and a highly diastereoselective Diels-Alder reaction with cyclopentadiene is the key step.

7-α-acetoxyhardwickiic acid: A furanoid clerodane

Abstract A new furanoid clerodane was isolated from ‘Copaiba oil’ and its structure was elucidated by spectral analysis and chemical correlation.

Experimental and theoretical study of a Diels–Alder reaction between a sugar-derived nitroalkene and cyclopentadiene

The Diels-Alder reaction of a pyranose-derived nitroalkene 1 with cyclopentadiene is described, and the unexpected facial selectivity of the cycloaddition is analyzed by a computational study.

Enantiospecific approach to a quinane skeleton related to pentalenolactones

Abstract A novel and general approach has been delineated for the enantiomerically pure synthesis of the angularly fused tricyclic system of the pentalenolactone family of compounds. D-Glucose is used as starting material and a diasteroselective Diels-Alder reaction sets the elements for the ring junctions.

Improved Synthesis of Methyl 4,6-O-Benzylidene-3-cyano-2,3-dideoxy-α-D-erythro-hex-2-enopyranoside and Methyl 4,6-O-Benzylidene-2,3-dideoxy-3-C-formyl-α-D-erythro-hex-2-enopyranoside

Abstract Simple and efficient route to the title compounds by using diethyl aluminium cyanide in benzene for the epoxide ring opening and the electrophilic assistance of LiCIO4 during the isomerization-elimination process.