It's as easy as 1, 2, 3: In a one-pot sequence, two stereocenters and three new bonds were created with high selectivity through an asymmetric alkynylation of acyl silanes, a tandem Brook-type rearrangement and Zn-ene-allene cyclization, the addition of an electrophile, and finally oxidation. The straightforward nature of the synthetic procedure contrasts strongly with the complexity of the densely functionalized products obtained.

Oestreich and colleagues present an approach to the chemoselective stepwise preparation of hydrosilanes with the general formula R 4-n SiH n where n = 1-3 and R can be different aryl and alkyl groups. The starting point is a bench-stable SiH 4 surrogate with two Si-H bonds masked as cyclohexa-2,5-dien-1-yl substituents. A sequence of palladium-catalyzed Si-H arylation and B(C 6 F 5 ) 3 -promoted deprotection and transfer hydrosilylation enables the programmable synthesis of hydrosilanes, even with three different substituents at the silicon atom.

An improved method for the dehydrogenative C-H/C-H cross-coupling at the C-7 position of indolines containing a urea as a directing group is reported. The new protocol is a rare example of an aerobic palladium(II)-catalyzed cross dehydrogenative coupling (CDC) reaction that proceeds at low temperature. The use of either Cu(OAc)2 in an open flask or dioxygen (balloon) at 50 °C tolerates indolines not substituted at C-2 and C-3, thereby extending the scope of the previous method that suffers from indoline-to-indole oxidation.

Diastereoisomerically pure (dr > 99:1) and enantiomerically enriched (er up to 98:2) substituted propargyl diols possessing a tertiary hydroxyl group were synthesized in a single-pot operation from simple acylsilanes through a combined catalytic enantioselective alkynylation of acylsilanes, followed by an allenyl-Zn-Brook rearrangement and Zn-ene-allene (or Zn-yne-allene) cyclization reaction. Two remarkable features of these reactions are the near complete transfer of chirality in the allenyl-Zn-Brook rearrangement and the highly organized six-membered transition state of the Zn-ene-allene carbocyclization found by DFT calculations. In this process, three new bonds and two new stereogenic centers are created in a single-pot operation in excellent diastereo- and enantiomeric ratios. DFT calculations show that the allenyl-Zn-Brook rearrangement occurs in preference to the classic [1,2]-Zn-Brook rearrangement owing to its significantly lower activation barrier.

The monosilane (SiH4) surrogate di­(cyclohexa-2,5-dien-1-yl)­silane is shown to be compatible with platinum-catalyzed hydrosilylation of α-olefins. The cyclohexa-2,5-dien-1-yl substituents in the monohydrosilylation adducts serve as protecting groups, and treatment with catalytic amounts of B­(C6F5)3 liberates the Si–H bonds along with benzene. By this, trihydrosilanes become accessible in two steps without the formation of salt waste.