Carbonylative and Hydrosilylative Carbocyclization of 1,5-Diynes for the Synthesis of Cyclic Dienones

Abstract

A rhodium complex, [Rh(acac)(CO)2], has been identified to catalyze the cyclization of various 1,5-diynes with hydrosilanes under an atmospheric pressure of carbon monoxide at room temperature. The cyclization of 1,5-diynes proceeds along with hydrosilylation and carbonylation to give derivatives of 2,5-dialkylidenecyclopentanone.

Ruthenium(0) Catalyzed Endiyne−α-Ketol [4 + 2] Cycloaddition: Convergent Assembly of Type II Polyketide Substructures via C–C Bond Forming Transfer Hydrogenation

“…These methods have been used to great effect to streamline total synthesis . In efforts toward a parallel suite of catalytic methods for Type II polyketide construction, we recently developed a Ru(0) catalyzed diene–diol [4 + 2] cycloaddition (Figure , eq 1). , Here, we report a redox-triggered [4 + 2] cycloaddition of 3,4-benzannulated 1,5-diynes (benzo-endiynes) − with α-ketols (Figure , eq 2) and demonstrate how this process may be applied to the convergent assembly of Type II polyketide substructures.…”

Hydroelementation of diynes

“…231 The mechanism of carbonylative cyclisation of 1,5-diynes 468 using [Rh(acac)(CO) 2 ] 204 started from silylrhodation, followed by the insertion of CO to 471 to form acylrhodium species 472, then acylrhodation to the second alkynyl group forms the 5-membered ring 473 (Scheme 91). 231 Cyclisation/hydrosilylation of 1,6-, 1,7-and 1,8-diynes 127a, 127o-p, 160, 164a, 474a-d was carried out in the presence of ionic Pd complex [(Z 3 -C 3 H 5 )Pd(cod)][PF 6 ] 476 with chlorodimethyl-305, dichloromethyl-357, and trichlorosilane 475. The reaction occurred at room temperature in CH 2 Cl 2 and products (Z)-1-methylene-2-silylmethylenecycloalkanes 477 were obtained in good yields, which were further transformed to their ethoxy analogs 478 (Scheme 92).…”

“…The products 469a-m were obtained with moderate or high yields 30-92%, which varies with both reagent structures (Scheme 90). 231 The mechanism of carbonylative cyclisation of 1,5-diynes 468 using [Rh(acac)(CO) 2 ] 204 started from silylrhodation, followed by the insertion of CO to 471 to form acylrhodium species 472, then acylrhodation to the second alkynyl group forms the 5-membered ring 473 (Scheme 91). 231 Cyclisation/hydrosilylation of 1,6-, 1,7-and 1,8-diynes 127a, 127o-p, 160, 164a, 474a-d was carried out in the presence of ionic Pd complex [(Z 3 -C 3 H 5 )Pd(cod)][PF 6 ] 476 with chlorodimethyl-305, dichloromethyl-357, and trichlorosilane 475.…”