Polarity-Reversible Conjugate Addition Tuned by Remote Electronic Effects

Abstract

A new concept, polarity-reversible conjugate addition, has been described, based on the findings that the polarity of a classical Michael acceptor can be reversed through remote electronic effects. In addition, the remote electronic effects are tunable, and both five-and sixmembered nitrogen rings can be constructed starting from acyclic precursors having the same enone structure unit simply by varying a remote substituent in the molecules.

Double nucleophilic attack on isocyanide carbon: a synthetic strategy for 7-aza-tetrahydroindoles

“…In the reaction, the ketene dithioacetal moiety is intact. 4 To our knowledge, the construction of 3a mentioned above represents the first example of one-pot synthesis of 7-aza-tetrahydroindoles from readily available acyclic precursors, which prompted us to find an efficient route to their synthesis from identical starting materials (i.e., N-aryl/alkyl-alkenoylacetamides (1) 4,5 and ethyl isocyanoacetate (2)) 6 by catalyst variation.…”

“…12 However, the direct synthesis of this heterocyclic skeleton remains a challenge. [8][9][10][11][12] The study described here reveals that 7-aza-tetrahydroindoles 3 (Table 2) and 6 (Scheme 3) can be synthesized in a single step from the reactions of ethyl isocyanoacetate 2 with a range of readily available N-aryl/alkyl-alkenoylacetamides 1 4,5 and 5 5,13 in an atom economical manner under mild conditions.…”

Unexpected Hydrobromic Acid‐Catalyzed CC Bond‐Forming Reactions and Facile Synthesis of Coumarins and Benzofurans Based on Ketene Dithioacetals

“…It was reported that the CC bond formation reaction of 1 and acid‐activated aldehydes can give the corresponding adducts efficiently (Scheme , conventional activation mode) 7. 8 As part of our studies on ketene dithioacetal chemistry,5a–e, 8, 9 we found that this kind of reaction was highly catalyst dependent 8. 9 In contrast to reactions promoted by BF 3 ⋅Et 2 O (50 mol %),7a EtAlCl 2 (100 mol %),7a or TiCl 4 (120 mol %),8a–c which would be consistent with the activation of aldehydes by Lewis or Brønsted acids with high catalyst loadings, the reactions of 1 with aldehydes under the catalysis of CuBr 2 were shown to involve α‐CH activation of ketene dithioacetals 1 (Scheme , nonconventional activation mode) 9.…”

α(δ')-Michael Addition of Alkyl Amines to Dimethyl (E)-hex-2-en-4-ynedioate: Synthesis of α,β-Dehydroamino Acid Derivatives

“…The Michael addition reaction, the regioselective 1,4-addition of nucleophiles to activated olefins, is one of the versatile methods used for C–C, C–N bond formation, and has found wide application in organic synthesis [1,2,3,4,5,6,7,8,9,10]. On the other hand, the anti -Michael or α-Michael addition reaction, the nucleophilic addition to the α-carbon of an activated olefinic compound, is also known in the literature [11,12,13]. The regioselectivity of the reactions can be reversed by the substitution of highly electron withdrawing groups at the β-position of the Michael acceptors [14,15].…”