α-Iodo-α,β-Unsaturated Ketones as Vicinal Dielectrophiles: Their Reactions with Dinucleophiles Provide New Annulation Protocols for the Formation of Carbo- and Heterocyclic Ring Systems

Abstract

α-Iodo-α,β-unsaturated ketones such as compound 1 serve as vicinal dielectrophiles and react with a range of dinucleophiles including pentane-2,4-dione and 1,3-indandione to produce [3 + 2]- and [2 + 1]-adducts such as 5 and 38, respectively. [4 + 2]- and [5 + 2]-cycloadducts have been obtained from compound 1 by related means. Preliminary studies reveal that α-iodinated α,β-unsaturated esters can also participate in at least some of these same processes.

A General Method to Access Underexplored Ylideneamino Sulfates as Interrupted Beckmann-Type Rearrangement Intermediates

“…The optimal conditions identified (Table 1, entry 1) required 2.0 equivalents of TBSAB in acetonitrile at 90 • C for 3 h, consistent with the O-sulfation of alcohol functional groups [30]. Due to a lack of commercially available oximes, 13 additional oximes were synthesized [32] from their respective ketones with hydroxylamine, in excellent yields of 90-99% (Chart 1). Due to a lack of commercially available oximes, 13 additional oximes were synthesized [32] from their respective ketones with hydroxylamine, in excellent yields of 90-99% (Chart 1).…”

“…Due to a lack of commercially available oximes, 13 additional oximes were synthesized [32] from their respective ketones with hydroxylamine, in excellent yields of 90-99% (Chart 1). Due to a lack of commercially available oximes, 13 additional oximes were synthesized [32] from their respective ketones with hydroxylamine, in excellent yields of 90-99% (Chart 1).…”

“…A plausible rationale is both the meta-positioning of the nitro group leading to a destabilizing delta-positive effect adjacent to the carbonyl group and reduced solubility of the halogen and nitro containing 2g and 2k. Due to a lack of commercially available oximes, 13 additional oximes were synthesized [32] from their respective ketones with hydroxylamine, in excellent yields of 90-99% (Chart 1).…”

Divergent synthesis of nitrocyclopropanes and isoxazoline N-oxides from nitro compounds and vinyl sulfonium salts

“…Next, nitrocyclopropanes can be obtained by a tandem Michael addition/ring-closure of either halo-nitroalkanes to Michael acceptors 10 (Scheme 1, part B, path 2) or primary nitro compounds to halo-substituted unsaturated carbonyl compounds (Scheme 1, part B, path 3). 11 Similarly, Fadel and coworkers utilized dibromosubstituted phosphonate as the 1,2-bis-electrophilic synthon. 12 Despite their versatility, such approaches are limited to the preparation of EWG-substituted cyclopropanes.…”