ISSN:
0009-2940
Keywords:
Diastereoselective synthesis
;
Homoallylic alcohols
;
1,3-Diols, homoallylic
;
β1-Hydroxyalkyl ketones
;
2,5-Dihydro-1H1-boroles
;
1,2-Oxaborolanes
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
1-Phenyl-3-borolenes CH2CR1=CR1CH2BPh) (1a: R1=H; b: R1=Me) react with aldehydes R2CHO to give cis-1,2-oxaborolanes CH2CR1[CR1(=CH2)]CR2R3OBPh (2, R2 = e.g. Me, Ph, CH=CH2, tBu, CCl3, R3 = H). Yields are nearly quantitative. Stereoselectivities usually are 100% (but only 95% for R2=CH=CH2, 97% for R2=Me). Oxidation with NaOH/H2O2 in THF affords homoallylic anti-1,3-diols HOCR2R31-CR1[CR1(=CH2)]CH2OH (3). An X-ray diffraction analysis of 3a (R2=p1-tolyl) proves the assigned stereochemistries. Ketones R2R3CO react analogously. Ketenes R2CCO form 5-alkylidene-4-vinyl-1,2-oxaborolanes (4), which tend to undergo double-bond migration. Oxidation produces two types of β1-hydroxylalkyl ketones R22CHCOC[(E)=CHMe]CH2OH (5) and R22CHCOCMe[CMe=CH2]CH2OH (6).
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19931260205
