Acylsilenes (3‐Oxo‐1‐sila‐1‐propenes) from Acyl(disilanyl)carbenes

UV photolysis of diazo(disilanyl)methyl ketones 2 in benzene generates acyl(disilanyl)carbenes 3, which rearrange to 3‐OxO‐1‐sila‐1‐propenes 4. The latter compounds are reactive intermediates which either cyclize to l‐oxa‐2‐sila‐3‐cyclobutenes 5 or form the eight‐membered cyclodimers 6, depending on the substituent of the acyl function. In a side reaction, isomerization of 4 to disilylketenes 7 takes place in some cases. On the other hand, photolysis of diazo ketone 13 yields both the l‐oxa‐2‐sila‐3‐cyclobutene 5a (via the acylsilene 14) and the adamantyl (trisilanyl)ketene 15 (by Wolff rearrangement).