01325nas a2200145   4500008004100000245015200041210006900193260000800262300001400270490000600284520072000290100001701010700002301027856012901050       2017                        eng d00aFormal [2+1] annulation (Spiro-Cyclopropanation) reaction between sulfur ylides derived from baylis-hillman bromides and arylidene indane-1,3-dione0 aFormal 21 annulation SpiroCyclopropanation reaction between sulf  cJUL  a6159-61620 v23 a<p>The sulfonium salts derived from the Baylis-Hillman bromides have been successfully employed for the selective cycloproporanation of arylidene indane-1,3-diones to synthesize densely substituted spiro-cyclopropanes in good to excellent yields (upto 94%). Products were obtained mostly in 1:1 diastereomeric ratio and were isolated in pure form. Diastereoselectivity has been improved by using suitably substituted starting materials. In this case a formal [2+1] annulation reaction competes over a probable [3+2] cycloaddition reaction. The reaction proceeds through a Michael initiated ring closure process of S-ylides to the activated olefins for the formation of structurally strained spiro-cyclopropanes.</p>1 aRoy, Suparna1 aPiradhi, Venkatesh  uhttps://library.ncl.res.in/content/formal-21-annulation-spiro-cyclopropanation-reaction-between-sulfur-ylides-derived-baylis