Efficient Method for the Synthesis of Polysubstituted Benzenes by One-Pot Tandem Reaction of Vinyl Malononitriles with Nitroolefins

Abstract

The one-pot synthesis of polysubstituted benzene derivatives was achieved via vinylogous Michael addition of vinyl malononitriles and nitroolefins as the key step and a sequential tandem reaction. A series of complex aryl compounds such as biphenyls and terphenyls can be obtained with satisfactory yields.

Synthesis of Phenanthrene Derivatives through the Reaction of an α,α‐Dicyanoolefin with α,β‐Unsaturated Carbonyl Compounds

“…As aconsequence,many approaches to this structure have been disclosed in the literature.T he traditional pathway is the Haworth synthesis,w hich contains aseries of stepsincluding FriedelÀCrafts acylation,followed by a Clemmensen reduction or WolffÀKishner reduction,c yclization, reduction, and dehydrogenation [11].O ther reliable strategiest op henanthrenes are intramolecular condensations of disubstituted biphenyls [12], photocyclization of stilbenes [ 13], Pd-catalyzed cyclization of aryneswith alkynes [14], base-catalyzedring transformation of 4-sec-amino-2-oxo-5,6-dihydro-2H-benzo[h]chromene-3-carbonitriles [15], carbanion-induced ring transformation of 2H-pyran-2-ones and 1-naphthalenone [16], and one-potm ulticomponent reactionsofaldehydes,malononitrile,1-tetralone,and NH 4 OH [17]. Most of these procedures suffer from the limitation of availability of precursors,l ow yields, harsh reaction conditions,a nd low functional group tolerance.Thev inylogous addition, av ariant of the Michael addition reaction [18], is a technicals trategy used for the formation of quaternary stereogenic centers [19], spirocarbocycles [20], and polysubstituted benzene derivatives [21].The high potential of a,a-dicyanoolefinsf or generationo fv inylogous carbanions has led them to readily react with different electrophiles,s uch as 1,2-diaza-1,3-dienes [22] …”

The multieffects of DMF and DBU on the [5 + 1] benzannulation of nitroethane and α‐alkenoyl ketene‐(S,S)‐acetals: Hydrogen bonding and electrostatic interactions

“…ÁÁÁO hydrogen bonds and electrostatic interactions between DBU-H 1 and O2 in TS [4][5] (Fig. 4 and Supporting Information Fig.…”

“…Thus, these hydrogen bonds promote the nucleophilic attack of C6 to C1. Moreover, we also calculated the charge transfer (CT) from the DBU-H 1 and DMF to the main reaction site for TS [4][5] . The CT value is 0.90e, which implies that TS 4-5 is considerably stabilized by DBU-H 1 and DMF in comparison with other TSs (see Fig.…”

“…S5 in the Supporting Information). Furthermore, a careful inspection of structure for TS [4][5] suggests that its own push-pull electron effects also contribute to the formation of the C1AC6 bond. The C5AC6 double bond is connected by both two electronwithdrawing carbonyl groups and two electron-donating alkylthio groups, thereby the C5AC6 double bond is highly polarized.…”

“…The C1 is also connected by one ANO 2 and one ACH 3 group, thus it is polarized. As a consequence, the push-pull electron effects reinforce the electrophilicity of C6 and nucleophilicity of C1, thus, accelerates the intramolecular cyclization of TS [4][5] . The subsequent CH 3 CH 2 SH elimination process includes two pathways, with (pathway 1) or without DMF (pathway 1 00 ).…”