Ketols s. Hydroxyketones

Keto-y-iactones s. y-Halogeno-y -keto-y-lactones Ketols s. Hydroxyketones N-Ketomethylpyridinium salts... 

Ketols s. Hydroxyketones Ketone cleavage of / -keto-carboxylic acid esters s. Ketones from / -keto-carboxylic acid esters Ketones (s. a. Oxo compounds) —alkylation 16, 862... 

Examination of A. qfficinarum by Itokawa and his group provided besides the known compound 6 (8) and the ketol 22 (25) two new enones, 28 and 29 (26). Circular dichroism studies revealed the interesting fact that, in contrast to the known components of Alms firma and A. sieboldiana, which contained (S)-6 and (5)-22, in Alpinia officinarum the same alcohols were present as the R enantiomers. On further investigation the same plant also yielded a total of eight new achiral or racemic diarylheptanoids 23, 24, 31 (27), 25, 26, and 30, (28), 33 (29), 27 and 32 (30). Since the highly susceptible P-hydroxyketones can readily undergo dehydration and subsequent addition of methanol, the enones 28, 29, and 30, as well as the P-methoxyketones 23, 25, and 26 may be artefacts. This assumption is also supported by the racemic nature of 23, 25, and 26. 

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