Kametani

Two approaches to convergent steroid syntheses are based on the thermal opening of benzocyclobutenes to the o-quinodimethane derivatives (see p. 80 W. Oppolzer, 1978 A) and their stereoselective intramolecular Diels-Alder cyclizations. T, Kametani (1977 B, 1978) obtained (+ )-estradiol in a six-step synthesis. The final Diels-Alder reaction occurred regio- and stereoselectively in almost quantitative yield, presumably because the exo transition state given below is highly favored over the endo state in which rings A and D would stcrically inter-... 

Carbon-oxygen bonds are formed by the Ullmann reaction (- coupling of aryl halides with copper) which has been varied in alkaloid chemistry to produce diaryl ethers instead of biaryls. This is achieved by the use of CuO in basic media (T. Kametani, 1969 R.W. Dos-kotch, 1971). 

The Diels-Alder reaction of o-quinodimethanes (from benzocyclobutenes) with nitrogen-ubstituted enes has also been applied to alkaloids synthesis (see p. 280f. T. Kametani, 1972, 1973, 1974 W. Oppolzer, 1978 A). 

Sept. 22, 1972), H. Kadowaki, M. Kametani, andT. Nakamura (to Nitto Chemical Industries Co.). 

H. Satoh, S. Kametani, and R. Yanagawa, GRldquid Pedox Sulfur Recovery Conference Austin, Tex., May 7—9,1989. 

Isoquinoline Alkaloids" Academic Press New York, 1972 (e) Kametani, T. In "The Total Synthesis of Natural Products" ApSimon, J., Ed. Wiley-... 

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