In the course of an unsuccessful attempt to prepare 2-(3,7-dimethylocta-I ,6-dienyl) -3hydroxy-l,4naphthoquinone (I a ) by acid catalyzed condensation of 2-hydroxy-l,4-naphthoquinone (2) with citronellal, a tetracyclic quinone (3) was obtained. This quinone was different from the two tetracyclic quinones, (4) and ( 5 ) , previously obtained from a triethylamine catalyzed reaction. The quinone (1 a) is shown to be an intermediate in the formation of ( 4) and ( 5). By adjusting the conditions ( l a ) can be isolated in a reasonable yield. Other 2hydroxy-3-alk-1 -enylnaphthoquinones are prepared similarly in variable yields. Primary and secondary products of this reaction are discussed.

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Bei Ionen‐ wie bei Radikalreaktionen scheint generell die effektive Molarität EM (= kintra/kinter) für Additionen sehr viel größer als für den Wasserstofftransfer zu sein. Werte für Radikalreaktionen wurden an Acyl‐tert‐butylnitroxiden ermittelt: Für den Transfer eines benzylischen H‐Atoms in 1 ergibt sich aus dem Vergleich mit der entsprechenden intermolekularen Reaktion ein EM‐Wert von 44 M, für die Addition von Radikalen an Alkene erhält man analog EM‐Werte von ca. 105 M.

When (-)-Norphos is used the main product is (-)-2, no second peak for (+)-2 being detectable in the gas chromatogram following the large (-)-2 peak. Catalysts made from ( + )-Norphos give predominantly ( + )-2. In this case the first peak in the chromatogram is that of the minor component (-)-2. Under these measurement conditions it was possible to determine the isomer ratio as 0.8:99.2, corresponding to an enantiomeric purity of 98.4% ee. With Diopbased catalysts in T H F at 35 "C no reaction occurred within 4 h. In benzene there was a reaction giving 2, but the enantiomeric purity was only about 20% ee. 2 The reaction of norbornadiene with acrylonitrile using Ni catalysts made from Diop or Norphos, giving 1, only occurs under harsh conditions, and gives a mixture of diastereomers with low asymmetric induction; it is not very suitable as a preparative method. The reaction of norbornadiene with phenylacetylene using Norphos-Co catalysts to give 2 proceeds under mild conditions and requires only small amounts of catalyst (0.2-0.3 mol %; norbornadiene:phenyiacetylene:Norphos:cobalt = 500:500: 1 S : l ) . The chemical yield is quantitative, with a remarkably high enantiomeric purity of 98.4% ee. The reaction of norbornadiene with phenylacetylene to give the deltacyclene 2 therefore ranks as one of the best enantioselective reactions catalyzed by transition-metal complexes that have so far been reported. Experimental Procedure4-PhenyI~etracycl0[4.3.0.0~~~.0~~~]non-4-ene 2: 0.95 mL (9.4 mmol) of norbornadiene and 1.00 mL (9.1 mmol) ofphenylacetylene were added under nitrogen to 7.1 mg (2 x 1 K 2 mmol) of Co(acac), and 14 mg (3 x 10.' mmol) of (+)-Norphos in 1 mL of dry THE The catalytically active Co species was then generated by adding 5 mL of a 1 M solution of diethylaluminum chloride in hexane. The reaction mixture was stirred for 4 h at 35 "C. 5 mL of isopropanol was then dripped in to decompose the Et,AICI. The volatile constituents were removed by vacuum distillation at room temperature. 2 was then isolated by vacuum distillation at 1OO' C in a Kugelrohr apparatus.[z]iO 56.3 (c = 1, CHCI,) The 'H NMR spectrum and mass spectrum of 2 were identical to those of a reference sample.[6] Yield 100%. enantiomeric purity 98.4% ee, both determined by gas chromatography with naphthalene as standard using a 40-m-Lipodex-C column [8] Retention times: (-1-2 120.7 min, (+)-2 123.7 min (column temperature 104"C, carrier gas H,. flow rate 4-5 mL min-' at 1.7 bar, injection temperature 17O'C). Received: February 2, 1990 [Z 3776 IE] German version: Angew. Chem. 102 (1990) 680 CAS Registry numbers: (-)-2. 127279-29-2; (+)-2, 127256-90-0; Co(acac),, 21679-46-9; norbornadiene, 121-46-0; phenylacetylene, 536-74-3; (+)-Norphos, 71042-54-1 ; diethylaluminum chloride, 96-10-6.Ed. En$ 18 (1979) 620.

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