Titanium Enolates of Thiazolidinethione Chiral Auxiliaries: Versatile Tools for Asymmetric Aldol Additions

Organic Letters

Volumn 2, Issue 6, 2000, Pages 775-777

  Crimmins, Michael T ^a   Chaudhary, Kleem ^a  

^a UNIVERSITY OF NORTH CAROLINA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

2-MERCAPTOTHIAZOLINE; ALDEHYDE; DYES, REAGENTS, INDICATORS, MARKERS AND BUFFERS; SPARTEINE; THIAZOLE DERIVATIVE; THIAZOLIDINE DERIVATIVE; THYROIDAN; TITANIUM;

ARTICLE; CHEMISTRY; METHODOLOGY; ORGANIC CHEMISTRY; STEREOISOMERISM;

ALDEHYDES; CHEMISTRY, ORGANIC; INDICATORS AND REAGENTS; SPARTEINE; STEREOISOMERISM; THIAZOLES; THIAZOLIDINES; TITANIUM;

EID: 0034704636     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol9913901     Document Type: Article

References (20)

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9. 2, and the combined extracts were dried over magnesium sulfate, filtered, and concentrated. HPLC analysis of the unpurified product revealed the isomer ratios. Purification by flash column chromatography afforded the major diastereomer.
10. Using 1.5 equiv of diamine gave selective formation of the Evans syn product, but 2 equiv resulted in better selectivity.
11. For a discussion of effects of amine structure on selectivity in Tin-(II) enolates, see: Mukaiyama, T.; Iwasawa, N. Chem Lett. 1984, 753-756.
12. The configuration of the aldol adducts was verified by correlation to authentic samples after removal of the auxiliary.
13. Aldehydes were freshly distilled prior to use.
14. 13C NMR and optical rotation. Yields are for isolated, chromatographically purified products.
15. Diasteromeric ratios were determined by HPLC.
16. Basha, A.; Lipton, M.; Weinreb, S. M. Tetrahedron Lett. 1997, 4171-4174. Levin, J. I.; Turos, E.; Weinreb, S. M. Synth. Commun. 1982, 12, 989-993.
17. Basha, A.; Lipton, M.; Weinreb, S. M. Tetrahedron Lett. 1997, 4171-4174. Levin, J. I.; Turos, E.; Weinreb, S. M. Synth. Commun. 1982, 12, 989-993.
18. Sano, S.; Kobayashi, Y.; Kondo, T.; Takebayashi, M.; Maruyama, S.; Fujita, T.; Nagao, Y. Tetrahedron Lett. 1995, 36, 2097-2100.
19. With oxazolidinethione auxiliaries, this product can also be obtained but the use of DMAP is required, see: Su, D.; Wang, Y.; Yan, T. Tetrahedron Lett. 1999, 40, 4197-4198.
20. This procedure cannot be used in the case of the aldehyde, which is easily epimerized under basic conditions.