5-Carbamoyl-3-pyridyl alkanol, asymmetric

As described, pyrimidyl alkanols 2 act as highly efficient asymmetric autocatalysts with significant amplification of chirality. 3-Quinolyl alkanoland 5-carbamoyl-3-pyridyl alkanol also serve as efficient asymmetric autocatalysts with amplification of chirality. 

Meanwhile, asymmetric autocatalysis of 3-quinolyl alkanol 84-86167,173 and 5-carbamoyl-3-pyridyl alkanol 77174 also proceed with amplification of . Quinolyl alkanols 84 with 9% increases its to 88%173 and the of 5-carbamoyl-3-pyridyl alkanol 77 increased from 14% to 87%174. 

Moreover, when these alkanols with low ee are utilized as asymmetric autocatalysts, 5-pyrimidyl alkanol 28 [48], 3-quinolyl alkanol [49],and 5-carbamoyl-3-pyridyl alkanols [50] with higher ees were obtained. The successive reactions were performed in order to make the best use of the autocatalysis, that is, the products of one round served as the asymmetric autocatalysts for the next. In the case of pyrimidyl alkanol, staring from (S)-alkanol 28a with only 2% ee, the ee reached almost 90% after four rounds [48] without the assistance of any other chiral auxiliary (Scheme 14). 2-Alkynyl-5-pyrimidyl alkanol 28b [5] and 2-... 

The introduction of a carbamoyl group to the 5-position of chiral 3-pyridyl alkanol enhances its efficacy as asymmetric autocatalyst. (S)-5-Carbamoyl-3-pyridyl alkanols 61 are automulti-plied with up to 86% ee in the enantioselective addition of i-Pr2Zn to 5-carbamoyl-3-pyridine-carbaldehyde 60 (Scheme 9.32) [60]. The enantioselectivity depends on the structure of the substituent on the nitrogen atom of the amide. A bulky t-Pr substituent is efficient for achieving high enantioselectivity. The amplification of the enantiopurity of 61 to a certain degree is also observed [61]. 

We found that chiral 5-pyrimidyl alkanol, 3-quinolyl alkanol and 5-carbamoyl-3-pyridyl alkanol are highly enantioselective asymmetric autocatalysts for the addition of z-Pr2Zn to the corresponding aldehydes, respectively. Among these, 2-alkynyl-5-pyrimidyl alkanol is a highly efficient asymmetric auto-... 

As described, it took us for 5 years to find pyrimidyl alkanol since the initial asymmetric autocatalysis of pyridyl alkanol of 1990. Soon after pyrimidyl alkanol, we also found efficient systems of asymmetric autocatalysis with 3-quinolyl alkanol [27] and 5-carbamoyl-3-pyridyl alkanol [28]. 

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