Dedicated to Professor Dieter Seebach on the occasion of his 65th birthday Two independent total syntheses of the Aristotelia alkaloid (À)-serratenone ((À)-1) are disclosed, one starting with (À)-a-pinene, the other one with (S)-a-terpineol. These correlations led to a revision of the originally proposed absolute configuration of the natural product. In the course of systematic investigations of the behavior of the indole alkaloids ()-makomakine (()-18) and (À)-hobartine ((À)-22) towards oxidizing reagents, it was found that treatment with I 2 leads to no less than five different products. Depending on the exact reaction conditions, each of them can be obtained as the major component in yields between 40 and 60%. One of these compounds was shown to be identical with the natural product ()-11,12-didehydromakonin-10-one (()-28).
Helvetica Chimica Acta ± Vol. 85 ( ) 3400 1 ) Part XV: see [1]. 2 ) Taken from the Ph.D. Theses of R. G. [2], M. D. [3], and R. G. [4]. 3 ) Taken from the Diploma Thesis of R. S. [5].
trans-verbenol ((À)-6) into bromoacetal (À)-7 (Scheme 2). In our hands, reduction of this intermediate with LiAlH 4 according to the original procedure invariably gave a 1 : 2 mixture of (À)-8 and ()-9, the undesired major product evidently arising via an S N 2' process. This is in contrast with the claim that, under these conditions, only (À)-8 is Helvetica Chimica Acta ± Vol. 85 (2002) 3401 Scheme 1 Mps (4-methoxyphenyl)sulfonyl, Dfb 2,6-difluorobenzyl Scheme 2 a) N-Bromosuccinimide (NBS), acetone. b) See text. c) Py ¥ TsOH, EtOH. d) NaH, 2,6-difluorobenzyl bromide, [15]crown-5, THF. e) HCOOH, 16 h at 238. f) Li, 4,4'-di(tert-butyl)biphenyl, THF, 2 h at À 708. g) Pyridinium chlorochromate (PCC) on Al 2 O 3 , CH 2 Cl 2 . h) CHCl 3 /H 2 O, 6 d at 238.