Investigation of a dialkylation approach for enantioselective construction of vicinal quaternary stereocenters

Organic Letters

Volumn 2, Issue 20, 2000, Pages 3241-3244

  Hoyt, Scott B ^a   Overman, Larry E ^a  

^a UNIVERSITY OF CALIFORNIA   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

DYES, REAGENTS, INDICATORS, MARKERS AND BUFFERS; INDOLE DERIVATIVE; PYRROLE DERIVATIVE;

ALKYLATION; ARTICLE; INFRARED SPECTROPHOTOMETRY; STEREOISOMERISM; SYNTHESIS;

ALKYLATION; INDICATORS AND REAGENTS; INDOLES; PYRROLES; SPECTROPHOTOMETRY, INFRARED; STEREOISOMERISM;

EID: 0034609674     PISSN: 15237060     EISSN: None     Source Type: Journal    
DOI: 10.1021/ol006494m     Document Type: Article

References (13)

1. Overman, L. E.; Paone, D. V.; Stearns, B. A. J. Am. Chem. Soc. 1999, 121, 7702-7703.
2. Overman, L. E.; Larrow, J. F.; Stearns, B. A.; Vance, J. M. Angew. Chem., Int. Ed. 2000, 39, 213-215.
3. For recent reviews of asymmetric synthesis of quaternary carbon centers, see: (a) Corey, E. J.; Guzman-Perez, A. Angew. Chem., Int. Ed. 1998, 37, 388-401.
4. (b) Fuji, K. Chem. Rev. 1993, 93, 2037-2066.
5. 2 As a result, it was unclear whether dienolate formation occurred faster than alkylation of a monoenolate.
6. Product ratios were determined by HPLC analysis using an Alltima silica column.
7. Link, J. T.; Overman, L. E. J. Am. Chem. Soc. 1996, 118, 8166-8167.
8. Prepared in standard fashion by triflating the corresponding known alcohol: Taunton, J.; Collins, J. L.; Schreiber, S. L. J. Am. Chem. Soc. 1996, 118, 10412-10422.
9. Reactions conducted using 0.5-1.0 equiv of 6 gave undesired dialkylated side products.
10. The TIPS group was removed with TBAF in THF/HOAc, the resulting alcohol was converted to the corresponding inflate, and this latter intermediate was cyclized in the presence of LHMDS to yield 3.
11. rel(MM2) kcal/mol 3 (0.0), 4 (3.0), 5 (4.8).
12. A recent survey of stereoselective C-C bond formation cites no examples in sections dealing with alkylation reactions with chiral electrophiles, see: Methoden Org. Chem. (Houben-Weyl, Workbook Edition), 4th ed.; 1996; Vol. E21/2, pp 1077-1118.
13. Examples of selectivity in the range of 7-10:1 using lactate Inflates were recently reported: Vedejs, E.; Daugulis, O. J. Am. Chem. Soc. 1999, 121, 5813-5814.