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Volumn 12, Issue 3, 2010, Pages 608-611

Catalytic (asymmetric) methylene transfer to aldehydes

Author keywords

[No Author keywords available]

Indexed keywords

ALDEHYDE; EPOXIDE; SULFIDE;

EID: 75749123420     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol902816w     Document Type: Article
Times cited : (35)

References (47)
  • 5
    • 75749125075 scopus 로고    scopus 로고
    • Recent reviews
    • Recent reviews:
  • 10
    • 75749121940 scopus 로고    scopus 로고
    • Selected representative examples
    • Selected representative examples:
  • 28
    • 75749103054 scopus 로고    scopus 로고
    • Hiyama et al. (ref 7a) claimed that 2 could be synthesized in 97% ee in the presence of a chiral phase transfer catalyst. However our group (ref 7b) recently demonstrated that Hiyama was in error and has actually observed the decomposition of the catalyst to a related epoxide (with a relatively large specific rotation) during the formation of 2 as a racemate
    • Hiyama et al. (ref 7a) claimed that 2 could be synthesized in 97% ee in the presence of a chiral phase transfer catalyst. However our group (ref 7b) recently demonstrated that Hiyama was in error and has actually observed the decomposition of the catalyst to a related epoxide (with a relatively large specific rotation) during the formation of 2 as a racemate:
  • 31
    • 75749136576 scopus 로고    scopus 로고
    • note
    • N2 ring closure to occur (see ref 9). It is notable however that in silico studies by Goodman (ref 10) on the enantioselective formation of styrene oxide from a semistabilized ylide derived from 4 and benzaldehyde found that the relative energies of the transition states of the intially formed betaines were excellent predictors of experimentally observed product enantioselectivity in the case studied. Thus, it cannot be ruled out that enantioselectivity can derive from kinetic control alone (i.e., facial selectivity in the attack of the ylide on the aldehyde) in these reactions, which would make the modest observed enantioselectivites associated with methylene transfer more difficult to explain.
  • 39
    • 75749083761 scopus 로고    scopus 로고
    • 1H NMR spectroscopy did not indicate the formation of methanol
    • 1H NMR spectroscopy did not indicate the formation of methanol.
  • 41
    • 75749137413 scopus 로고    scopus 로고
    • Phosphazene bases have been previously used in stoichiometric CC reactions involving semistabilsed ylides, for examples see
    • Phosphazene bases have been previously used in stoichiometric CC reactions involving semistabilsed ylides, for examples see:
  • 46
    • 75749088985 scopus 로고    scopus 로고
    • A key predictor of success in these experiments is having prior knowledge of the interval required to ensure complete alkylation of 9 (20 mol%) by MeOTf (20 mol%) at the concentration to be used in the epoxidation protocol.
    • A key predictor of success in these experiments is having prior knowledge of the interval required to ensure complete alkylation of 9 (20 mol%) by MeOTf (20 mol%) at the concentration to be used in the epoxidation protocol.
  • 47
    • 75749129529 scopus 로고    scopus 로고
    • Enantioselectivity in these reactions is strongly dependent on the steric bulk of the sulfide substituents; for instance, in an epoxidation experiment using a stoichiometric amount of the methyltriflate salt of a 2,5-dimethyl analogue of 27, (S)-2 was isolated in 1% ee.
    • Enantioselectivity in these reactions is strongly dependent on the steric bulk of the sulfide substituents; for instance, in an epoxidation experiment using a stoichiometric amount of the methyltriflate salt of a 2,5-dimethyl analogue of 27, (S)-2 was isolated in 1% ee.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.