2-Bromo-3-trimethylsilylpropene. An annulating agent for five

Barry M. Trost, and Brian P. Coppola. J. Am. Chem. Soc. , 1982, 104 (24), pp 6879–6881. DOI: 10.1021/ja00388a112. Publication Date: December 1982...
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J . Am. Chem. Soc. 1982, 104, 6879-6881 Scheme I1 KI3CN

a,b,c

2-Bromo-3-(trimethylsilyl)propene. An Annulating Agent for Five-Membered Carbo- and Heterocycles

-

(CH,’3C0,CH,CH3),

70% c t t 30% C C t h i

,

uu j,k,l,m,n*

6879

II II

CH3CCCH3-I3Co,

BrCH,CH,Br, K1, CH,CH,OH, A. H,SO,, A. C,H, (-H,O), CH,CH,OH, A (50% overall). LiAlH,, THF (8570). e 40% HBr, H,SO, (80%). f (C,H,),P (82%). gn-BuLi, THF, cis-oct-4-enedial (35%). Br,, CH,Cl,, CH,COOH (73%). NaOCH,CH,OH, HOCH,CH,OH, THF, A (15%). 500 “C, 45 Br,, CH,CI,. H,, Pd/C. O,, torr of N,, 10 mL/min flow. CH,COCH,. (CH,),S.

’

Table 1. Calculated and Experimentala Relative Peak Intensities (in %) for the M’ Peak of Butanedione according to Various Mechanisms observed for unlabeled predicted butane- [ 2 + for spiro- ranm/e dione 2 + 21 [3.3] [3.3] dom obsd 86 96 39 41.2 44 41.5 51.5 59 49 58.5 87 4.0 34 42.4 88 0.0 14.5 2 10.3 7