Boryl-3-propenoic acid derivatives

The intramolecular Diels-Alder reactions involving boryl-3-propenoic acid derivatives has been addressed to. So, heating the trienylamide (7) at 80°C in toluene for 15 hours led to a 1/3 mixture of the cycloadducts (8) and (8 ) isolated in 72 % yield (figure 6) l7. The trienylamide (9) could not be isolated since the IMDA occured at the temperature of the coupling step, i,e below 0°C in ether for 30 minutes. This very fast cyclisation led to a 85/15 mixture of cycloadducts (10) and (10 ) having respectively a cis and trans junction in the bicyclic structure. The cis bicyclic structure (10) results from an endo approach of the diene and the dienophile. This is in agreement with literature data l8. 

Narasaka and Yamamoto applied catalyst 406 in the cycloaddition of l-acetoxy-3-methyl-1,3-butadiene (409) to 3-boryl propenoic acid derivative 410 (equation 122). Cycloadduct 411 was employed in the total synthesis of (-l-)-paniculide254. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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