Ca(fBuN=CHCH=NtBu) 4 ( -120'C): C,,H,,CaN,, monoclinic, P2,/r, M = 420.68 gmol-', a = 2077.7(2), b =1769.3(3), c =1360.4(3) pm, fl =103.91(1~, V = 4.854 nm3, pcrlE,, = 1.15 gem-', F(000) = 1840, 2 = 8, ~(Mo,, graphite monochromator, b =71.073 pm) = 0.27 mm-'. The data collection was performed on a Siemens-Stoe AED2 diffractometer. Crystal size 0.3 x 0.3 x 0.4 mm; 8834 reflections of which 6422 were independent and 3927 observed with F > 4oF; 2@,,, = 45"; structure determination with direct methods (SHELXS-92 [13]); refinement of 618 parameters with all data and with 1060 restraints according to F 2 ; wR2 (all data) = 0.302, R1 = 0.098. residual electron density 1.15 x 10' and -0.83 x 10' enm-3, respectively. The asymmetric unit contains two crystallographically inde-[Z 5907 IE]

A third mode of reactivity for allylsilanes in their reactions with α,β‐unsaturated carbonyl compounds has been found in addition to the Sakurai reaction and the [3 + 2] cycloaddition. Silylmethyl‐cyclobutanes are formed regioselectively via a siliranium ion intermediate (1). The reaction with methyl propynoate provides bicyclo[2.2.0]hexanes in a one‐pot conversion.

No abstract

No abstract

No abstract