15 V. 74) Sismmary. A total of 68 constituents, mainly aldehydes, ketones and esters, have been identifird for the first time in a black tea aroma concentrate using coupled gas-chromatography/ mass spectrometry. Introduction. -Tea is one of the world's most widely consumed beverages [l] 1) Two recent reviews by Sanderson &Graham [Z] and Sanderson [3] are a good introduction to the tea literature. For the most recent work on black tea aroma since the latest review [2], see [41 [51 FI.

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The preparation of the vitispiranes 9 and 10, identified among the volatiles of vanilla, from the theaspiranes 1 and 2 via the intermediates 4 and 5 and the allyl alcohols 7 and 8, respectively, is described. The theaspiranes 1 and 2 can be obtained from the compounds 11–15 or 24–26.

SummaryThe preparation of the vitispiranes 9 and 10, identified among the volatiles of vanilla, from the theaspiranes 1 and 2 via the intermediates 4 and 5 and the allyl alcohols 7 and 8, respectively, is described. The theaspiranes 1 and 2 can be obtained from the compounds 11-15 or 24-26.Vitispirane') (9/10), one of the most recently discovered ionone-like spiro-ethers, was identified in the volatiles of grape juice and distilled grape spirits, and in table and fortified wines [I]. We found the diastereoisomers 9 and 10 of vitispirane to be important aroma components of vanilla. Gas-chromatographic (GC.) analysis of the volatiles of a vanilla extract on a glass capillary column UCON HB 5 100 revealed the presence of the mixture 9/10 in the region between acetophenone and 5-methylfurfural. It appeared in an incompletely resolved double peak in which the ratio of 9 and 10 was about 1:32). The isomers showed practically identical mass spectra [ 11.Since it was not possible to separate 9 and 10 by preparative GC., stereoselective synthesis was undertaken. The naturally occurring theaspiranes'), a mixture of the diastereoisomeric 1 and 2 [2-41 which unlike vitispirane (9/10) can be separated by fractional distillation, were the suitable starting material. Separate treatment of cisand trans-theaspirane (1 and 2, re~pectively)~) with m-chloroperbenzoic acid yielded varying proportions of the diastereoisomeric epoxides 3 and 4, and 5 and 6, respectively, which were separated [6]. When treated with aluminium triisopropoxide at 140°, the main epoxidation products 4 and 54) gave in excellent yield exclusively the racemic allyl alcohols 7 and ti5), respectively. 7 (m.p. 70-71"), when treated with cold POCl,/pyridine, yielded cis-vitispirane (9) in over 50% yield, its diastereol) *) 3, 4, 5,For systematic names see exper. part. The NMR. spectra of the natural products show that the discoverers [l] of vitispirane also had a mixture of diastereoisomers. We thank Dr. Williams for this information and the spectra. The configuration of the theaspiranes 1 and 2 has already been established by direct linking with the known cis-and trans-theaspirone, respectively [5]. These products were also isolated from tea flavour [4] (cf. also [7]). The optically active compounds have been prepared independently in the same way [8]. We thank Drs. Kaiser and Lumparsky for the communication of the conference manuscript.

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