Multidirectional Cobalt-Catalyzed Diels–Alder/1,4-Hydrovinylation Sequences

Abstract

The combination of two powerful cobalt-catalyzed carbon-carbon bond forming transformations, namely, the Diels-Alder and the 1,4-hydrovinylation reaction, in a tandem or a sequential one-pot procedure, opened up a concise and efficient route to polysubstituted aromatic systems and cyclohex-3-enone derivatives. Furthermore, ozonolysis of the latter products led to polycarbonyl compounds with tailored carbonyl group distances which could be characterized via their respective BF(2)-borinane complexes. The cobalt catalysts tolerated several functional groups, and a flexible approach to polyfunctionalized compounds in concise fashion was described.

1,4‐Cyclohexadienes—Easy Access to a Versatile Building Block via Transition‐Metal‐Catalysed Diels–Alder Reactions

“…In a recent application of an allylic boronic ester intermediate, Hilt and Erver realised a sequential four‐ and even a five‐component reaction sequence initiated by the formation of a multiply functionalised 1,4‐cyclohexadiene derivative (Scheme ) . The key building block for the synthesis of complex molecules such as 39 is the boron‐functionalised isoprene 35 .…”

“…The thereby generated 1,4‐cyclohexadiene intermediates can be treated with acid and ozonolysis led to ring opening rather than scission of the carbon backbone. Accordingly, 1,3,6‐tricarbonyl derivatives, such as 43 , were generated in good yields in a short reaction sequence (Scheme ) …”

Synthesis of Non-Conjugated Trienes via In Situ Hydrovinylation/Wittig Olefination of Unsaturated Phosphonium Salts

“…IR (neat): 3018, 2922IR (neat): 3018, , 1645IR (neat): 3018, , 1617IR (neat): 3018, , 1493IR (neat): 3018, , 1440IR (neat): 3018, , 1323IR (neat): 3018, , 1262IR (neat): 3018, , 1162IR (neat): 3018, , 1117IR (neat): 3018, , 1065IR (neat): 3018, , 1019, 501 cm -1 . 4,145.1,137.7,132.2,129.4,129.0,128.9,128.8,128.6,128.3,126.7,126.1,125.5 (q,J = 3.7 Hz),110.6,36.5,34.1,33.3,26.9; the quarternary CF 3 atom was not detectable.…”

“…2,3 As shown in the literature, the hydrovinylation reaction is suited to a selection of in situ follow-up reactions, such as allylboration reactions or ozonolysis, gaining access to unsaturated target structures as synthons for products with higher functional demand and complexity. 4,5 To the best of our knowledge, phosphorus-containing starting materials have not yet been applied to the synthesis of non-conjugated trienes (Scheme 1). 6 Non-conjugated polyenes are versatile building blocks for targeted functionalisation due to the characteristic electronic properties and location of differently substituted double bonds.…”

Cobalt‐Catalyzed Multi‐Component Reactions: Recent Advances and Perspectives in Organic Synthesis

“…Hilt's group also demonstrated a tandem one-pot procedure consisting Diels-Alder and 1,4-hydrovinylation reactions for the synthesis of multi-substituted aromatic systems and derivatives of cyclohex-3-enone through cobalt catalysis in excellent yields (Scheme 32). [40] Moreover, polycarbonyl compounds could be obtained through ozonolysis of cyclohex-3enone derivatives. Aromatic enynes could access the target products in excellent yields while substrates with ketone functional groups could provide lower yields.…”