The synthesis of sinigrin

The synthesis of novel hexa-13C-labelled glucosinolates from [13C6]-d-glucose

“…With the hexa- 13 C-labelled thioglucose in hand, subsequent work concentrated on its coupling with the hydroximoyl chloride (Scheme 2), a protocol initially established by Benn et al 20 Phenethylhydroximoyl chloride (5a) derived from phenylpropionaldehyde oxime in DCM in the presence of half an equivalent of pyridine or triethylamine was known to be unstable and has to be prepared immediately before the coupling. We reasoned that the instability of this compound lies in the presence of organic base, which catalyses the premature removal of HCl and formation of the nitrile oxide.…”

“…Coupling of this 13 C-labelled thioglucopyranose with various hydroximoyl chlorides would afford any glucosinolate in another three-step sequence. Herein three typical hexa- 13 C-labelled glucosinolates were synthesised according to our standard methodology for glucosinolates, 14,19,20 after optimisation using unlabelled materials.…”

The synthesis and enzymic hydrolysis of (E)-2-[2,3-2H2]propenyl glucosinolate: Confirmation of the rearrangement of the thiohydroximate moiety

“…The product was purified by flash silica chromatography by elution with hexane:ethylacetate (60:40) and then hexane:ethylacetate (50:50) to give a white amorphous solid (800 mg, 54% yield; m.p. 165-166°C [lit 165-166°C (Abramski and Chmielewski, 1996), 164-165°C (Benn and Ettlinger, 1965) 4.6. S-(2,3,4,6-Tetra-O-acetyl-1-thio-b-D-glucopyranosyl)-O-(potassium sulfonato)-(E)-[3 0 ,4 0 -2 H 2 ]but-3 0 -enethiohydroximate 2,3,4,6-Tetra-O-acetyl-1-thio-b-D-glucopyranosyl-(E)-[3 0 , 4 0 -2 H 2 ]but-3 0 -enethiohydroximate (300 mg, 0.67 mmol) was added to freshly prepared pyridine sulfur-trioxide complex (334 mg, 2.1 mmol) in anhydrous pyridine (3.1 ml) and left at room temperature for 48 h. The pyridine solution was poured onto a solution of potassium bicarbonate (0.423 g in 2.5 ml water) and stirred for 20 min.…”

“…This synthesis was improved to produce large amounts of 2-propenyl glucosinolate (Abramski and Chmielewski, 1996) using essentially the same route as Benn and Ettlinger (1965). The formation of thiocyanates has been studied in some detail by Luthy and Benn (1977), who used a Thlaspi arvense seed flour extract to show that 2-[1-14 C]propenyl glucosinolate is converted to the 3-thiocyanato[3-14 C] prop-1-ene.…”

“…2-Propenyl glucosinolate (sinigrin) has previously been synthesised by Benn and Ettlinger using the nitro route to the chloro-oxime (Benn and Ettlinger, 1965). This synthesis was improved to produce large amounts of 2-propenyl glucosinolate (Abramski and Chmielewski, 1996) using essentially the same route as Benn and Ettlinger (1965).…”