Grieco elimination

Selenoxides undergo elimination at temperatures even lower than room temperature. The Grieco elimination is an organic reaction describing the elimination reaction of an aliphatic primary alcohol through a selenide to a terminal alkene. 

SCHEME 8 Selective deprotection of ent-5 and Grieco elimination to form ent-4. 

The same elimination has been effected by Corey and Grieco with mesyl chloride (see Methanesulfonyl chloride, this volume). 

Catalytic hydrogenation of 18 afforded colartin (19). Introduction of the a-methylene-y-lactone moiety by the Grieco procedure allowed the isolation of arbusculin A (21) in 65% yield. In a similar way the minor fi-diol 16 was transformed into 25 and 27. In this case, treatment of mesylate 22 partially afforded the 3a-bromide 23, which did not undergo the elimination reaction described above. 

In the saussurea lactone synthesis by Grieco (Scheme 31) [18], cleavage of the C(2)-C(3) link was carried out by ozonolysis of the C(2)-C(3) double bond in compound 247, obtained regioselectively from tetrahydrosantonin 3b by a Shapiro reaction, to give diol 51. Subsequent elimination of both hycftoxyl groups in several steps yielded saussurea lactone (56). An improvement of tWs procedure, described by our group [17], was based on the transformation of diol 51 into diselenide 52, which could then be transformed directly into saussurea lactone (56) (see Scheme 8). 

The Grieco-Sharpless elimination provides a mild and powerful method for dehydrating primary alcohols to terminal alkenes, as exemplified by the following reaction sequence ... 

In an examination of a route to a key intermediate (101) for PGA synthesis starting from iodolactone (99) (Scheme 20), Corey and Grieco have disclosed a novel elimination reaction, which may be mechanistically related to Comforth s olefin synthesis. The eliminationreactioninvolves the conversion of (99) in pyridine into (100) by treatment with methanesulphonyl chloride at —20 °C. The average yield per step for the conversion of (99) into (101) was 94% and thus makes the PGA precursor (101) very readily available. 

Grieco, P. A. Gilman, S. Nishizawa, M. Organoselenium Chemistry. A Facile One-Step Synthesis of Alkyl Aryl Selenides from Alcohols /. Or. Chem. 1976, 41, 1485-1486. Sharpless, K. B. Young, M. W. Olefin Synthesis. Rate Enhancement of the Elimination of Alkyl Aryl Selenoxides by Electron-Withdrawing Substituents / Or . Chem. 1975, 40, 947-949. 

For related sulfoxide to olefin transformations, see B. M. Trost and T. N. Saizmann, ). Amer. Chem. Soc., 95, 5321 (1973). Recently, P. A. Grieco and J. J. Reap (Tetrahedron Lett., 1097 (1974)] have reported a novel a-methylenation sequence, based on the thermal elimination of a-phenylsulfinyl lactones to a-methylene-T-butyrolactones (i-4i). 

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