Microwave-Accelerated Competing Domino Processes: A Tether-Controlled Dual Pathway into High Molecular Complexity

Abstract

Bicyclic unsaturated diols undergo a path selective modular domino transformation upon subjection to Pb(OAc)4, the reaction being biased to the nature of the angular substituent. The magnitude of the linking chain and the nature of the angular substituent determine the reaction course. Methylene ether linkage acts as an autoremovable directing group (ring-retained domino product 5), whereas a propylene linkage switches the path toward the ring-expanded type 21 domino product. Reaction times were substantially reduced using microwave irradiation.

Experimental and computational study of the ring opening of tricyclic oxanorbornenes to polyhydro isoindole phosphonates

“…(8) 53.86 (d, J CP = 6.9 Hz, OCH 3 ), 54.27 (d, J CP = 6.9 Hz, OCH 3 ), 54.82 (CH 2 N), 61.46 (d, J CP = 156.9 Hz, CHP), 92.64 (C q Cl 3 ), 110.29 (CH arom C q,arom OH), 120.63 (C q,arom Cl), 124.53 (d, J CP = 5.8 Hz, C q,arom CH 2 ), 124.64 (d, J CP = 3.5 Hz, CH arom C q,arom Cl), 137.44 (d, J = 4.6 Hz, C q,arom CHP), 152.81 (C q,arom OH), 159. 61 Ring opening using Fe 3+ -montmorillonite. General procedure for the ring opening with K10-FeAA120.…”

“…1 2 J HH coupling constants of the cyclohexene ring of the major isomer 17 and comparison with compound 19 from literature. 61 The endo isomer 4¢¢, was ring opened under the same reaction conditions. In this case no aromatic products were formed.…”

Stimulating excursions into organolead chemistry: modular domino sequences triggered by oxidative cleavage

“…The tendency of the organolead intermediates i-viii, bearing an alkoxy-angular substituent, to rearrange with ring expansion is directly related to the cyclic oxonium's ring size (furylium, pyranylium, oxepanium); that is the length of the linking chain. 81 The oxonium pathway is severely compromised as the tether length and the bulk of the ether protective group increase. Employing a bulky protecting group such as trityl (Tr) 6Sbm gives excellent control of regioselectivity in favor of 8Sbm.…”

Modular Construction of Topologically Complex Polycyclic Acetals by Tether‐Controlled Domino Reactions

“…Our investigations resulted in efficient ways to construct complex molecular frameworks in one pot by planned combination of reactive groups placed at the angular position. Thus, it is possible to select a ring‐expanding path,2 a hetero[4π+2π+2π]cycloaddition,3 a ring‐retentive oxonium path,4 or a hetero[4+3+2]cycloaddition5 by varying the functional group at the angular position or simply to interrupt the process at the [4π+2π] stage 6. Establishing a fundamental mechanistic understanding in these domino reactions,7 discovered by serendipity, led to the development of new variations and improved our capacity to predict reactivity.…”