Cyclododecene isomeric separation by (supported) rhodium(i)-catalysed selective dehydrogenative borylation reaction

Abstract

Cyclododecene, commercially available as a cis/trans mixture, reacts with dipinacolborane (BPin)2 only through the cis isomer, during the Rh(I)-XantPhos catalyzed dehydrogenative monoborylation reaction, leaving untouched the starting trans-cyclododecene. In this...

One-Pot Synthesis of Terminal Alkynes from Alkenes

“…These results are valid for designing the one-pot strategy toward the synthesis of the final terminal alkynes. Despite the Ru-catalyzed dehydrogenative silylation reaction did not work for internal alkenes, neither aryl nor alkyl (Figure S5, top), the implementation of other dehydrogenative reactions such as the dehydrogenative borylation of internal alkenes , may lead to the synthesis of internal alkynes (see next section).…”

“…At this point, a second alternative was considered, i.e., the dehydrogenative monoborylation reaction of alkenes . We reproduced the conditions of the dehydrogenative monoborylation reaction described for cis -stilbene SI-8 and cyclododecene SI-9 , and the catalytic results (Table S5) show that only the vinyl boronate of the latter could be obtained with this method, in good yield (93%).…”

“…At this point, a second alternative was considered, i.e., the dehydrogenative monoborylation reaction of alkenes . We reproduced the conditions of the dehydrogenative monoborylation reaction described for cis -stilbene SI-8 and cyclododecene SI-9 , and the catalytic results (Table S5) show that only the vinyl boronate of the latter could be obtained with this method, in good yield (93%). The oxidative dehydroelimination reaction of this vinyl was tested under the optimized reaction conditions described above for vinyl silanes (see ahead, i.e., Figure ); however, a conversion of 44.9% and an overall yield of isolated product of just 4.0% was achieved.…”

The Overlooked Potential of Sulfated Zirconia: Reexamining Solid Superacidity Toward the Controlled Depolymerization of Polyolefins

“…For example, solid porosity allows control of stereo- and regioselectivity not available in liquid acids through effects influencing substrate orientation, reactive intermediate size, mass transfer, and intermediate stabilization . The classic example is the shape selectivity associated with zeolite catalysts of varying pore dimensions and pore connectivity. ,, These principles have been extended to polymer deconstruction reactions using supported metals in the zeolite pores, with recent examples employing dehydrogenation to initiate C–C bond cleavage and C–H borylation reactions. − Zeolites can both naturally and synthetically occur as 2D sheets (e.g., MMT) and/or 3D interconnecting porous networks (e.g., HZSM-5). , As previously discussed, acid-catalyzed depolymerization of PP generates an uncontrolled mixture of primarily paraffin products on solid acids with little pore volume (e.g., SZrO). However, the ordered, 0.55 nm, high-volume pores of HZSM-5 promote chain-end β -scission and sterically impede formation of the bulky intermediates produced by SZrO that generate heavier paraffin products .…”