Methylfuran-2-carbaldehyde

Knoevenagel condensation of the corresponding 3-methylfuran-2-carbaldehyde 379 and 3-methybenzo[4]furan-2-carbaldehyde 382 with diethyl malonate followed by bromination with iV-bromosuccinimide (NBS) in the presence of dibenzoyl peroxide afforded bromides 380 and 383, respectively. Treatment of 380 and 383 with benzylamine, isopropylamine, /-butylamine 3-hydroxypropylamine, aniline and -toluidine in ethanol yielded furo[2,3-c]pyrroles 381 and benzo[4,5]furo[2,3-c]pyrroles 384, respectively (Scheme 41). The yields of furopyrroles 381 are only moderate (16-46%), because these compounds are highly sensitive to acid, and partially polymerized upon silica... 

Furancarboxaldehyde, 3-methyl-, 3-methylfuran-2-carbaldehyde, 3-methy -2-furaldehyde, 3-methy 1-2-furfural [33342-48-2)... 

Furancarboxaldehyde, 4-methyl-, 4-methylfuran-2-carbaldehyde, 4-methyl-2-furaldehyde, 4-methy 1-2-furfural [33342-49-3 ... 

The formation of 5-hydroxymethylfuran-2-carbaldehyde from saccharose proceeds via hydrolysis to fructofuranosyl cation and glucose (Figure 4.26). Ehmination of a proton and two molecules of water from the fructofuranosyl cation yields 5-hydroxymethylfuran-2-carbaldehyde. Under dry pyrolytic conditions and at temperatures above 250 °C, 90% of 5-hydroxymethylfuran-2-carbaldehyde originates from the fructose moiety and only 10% originates from glucose. Pentoses and L-ascorbic acid dehydrate in the same way as hexoses under addic conditions yielding furan-2-carbaldehyde (via reactive 3-deoxy-L-t/jreo-pentos-2-ulose and 3,4-dideoxypentosulos-3-ene) as the main product (see Section 5.14.6.1.5). 6-Deoxyhexoses, such as L-rhamnose, yield, analogously, 5-methylfuran-2-carbaldehyde (4-195). 

A large number of furan derivatives are produced in non-enzymatic browning reactions as dehydration products of carbohydrates and related compounds, such as ascorbic acid (y-lactones can also be considered furan derivatives). Most furans are common to many thermally processed foods. Higher levels of these compounds are also present in acid protein hydrolysates. Furan-2-carbaldehyde has the characteristic pleasant woody aroma resembling nuts, which arises from pentoses and ascorbic acid, and 5-methylfuran-2-carbaldehyde, which is a product of 6-deoxyhexoses. A fatty herbal type flavour is provided by 5-hydroxymethylfuran-2-carbaldehyde arising from hexoses. 2-Acetylfuran arising from hexoses and pentoses is an important component of a number... 

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