Bno CHO 3-Benzyloxypropionaldehyde (6: Dimethyl sulfoxide (3.90 mL, 4.29 g. 55 m
ID: 519158 • Letter: B
Question
Bno CHO 3-Benzyloxypropionaldehyde (6: Dimethyl sulfoxide (3.90 mL, 4.29 g. 55 mmol) was added in a dropwise fashion to a solution of oxalyl chloride (4.40 mL, 6.40 g, 50 mmolo in methylene chloride (240 mL cooled to -78 oc. he solution was stirred for 15 min followed by dropwise addition of a solution of benzyloxy-1-propanol (4.00 mL, 4.20 g, 25 mmol) in methylene chloride (10 mL). After addition was complete was the mixture stirred an additional 15 min. Triethylamine (21.0 mL, 15.2 g, 150 mmol) then added was in a dropwise fashion and the mixture allowed to stir for a further 15 min. Following this the cold bath was removed and the mixture allowed to warm to room temperature. The mixture was diluted with diethyl ether and washed with water (3x), dried (Mgso filtered and concentrated to an oil. Chromatography (20% diethyl etherl pent yielded 4.06 g (99%) of 3-benzyloxypropionaldehyde 6 as a oil. H NMR matched thatExplanation / Answer
The authors have prepared alkoxysulfonium ion intermediate now. The technique is abstraction of a proton from the alkoxysulfonium ion which will take the reaction forward leading to the carbonyl compound.
The addition of triethylamine (more than two eq) will deprotonate the alkoxysulfonium ion to give a sulphur ylide. In a five member ring transition state this sulphur ylide decomposes to give dimethyl sulfide and the desired product aldehyde. The addition of triethyl amine followed by stirring for 15 minutes and removal of cold bath leading to room temperature indicates the completion of the oxidation reaction.