188251-24-3

Upstream product

• 17451-21-7 (E)-4-(4-methoxy-phenyl)-2-oxo-3-butenoic acid 
• 188251-56-1 (3R,4R)-3-(tert-Butyl-diphenyl-silanyloxy)-4-hydroxy-dihydro-furan-2-one 
• 58479-61-1 tert-butylchlorodiphenylsilane 

Downstream Products

• 193675-15-9 (2S,4R,6R)-4,6-Bis-(4-methoxy-phenyl)-tetrahydro-pyran-2-carboxylic acid 
• 193827-87-1 (2R,4R)-2,4-Bis-(4-methoxy-phenyl)-3,4-dihydro-2H-pyran 
• 136031-29-3 (-)-sugiresinol dimethyl ether 

Relevant academic research and scientific papers

Asymmetric endoselective [4+2] heterocycloadditions of styrene dienophiles with chiral benzylidenepyruvic esters. Total synthesis of (-)-O-dimethylsugiresinol

Eu(fod)3 catalyzed [4+2] heterocycloadditions of para-methoxystyrene 7 with esters 8a-f of benzylidenepyruvic acids (deriving from various chiral alcohols) furnished endo adducts 9a-f with variable diastereoselective ratios (from 58/42 to 86/14). Interestingly, the benzylidenepyruvic esters 8g and 8h, deriving from a new chiral vector, the α-O-silyl ether 6 of (D)-(-)-erythronolactone 5, gave the corresponding endo adducts 9g and 9h with a high diastereoselective ratio (dr ≤95/5). The adduct 9h was used as a precursor in a five-step synthesis of 'natural' (-)-dimethylsugiresinol (1b).

Lignans.19. Total synthesis of (-)-O-dimethylsugiresinol, involving asymmetric [4+2] heterocycloaddition of a styrene with a benzylidenepyruvic ester of an α-O-silyl derivative of (D)-erythronolactone

α-O-t-Butyldiphenylsilyl-(D)-erythronolactone [(+)-25] (a new chiral vector) was esterified with 4-methoxybenzylidene pyruvic acid (19). Eu(fod)3 catalyzed [4+2] heterocycloaddition of the latter 1-oxabutadiene with 4- methoxystyrene (as the dienophile), afforded high yields of the endo adduct 23c with 95/5 diastereofacial ratio. Five further steps led to enantiomerically pure natural (-)-O-dimethylsugiresinol (-)-2 in 12% overall yield from the acid 19.