Preparation of 2-Iodo-1,3-butadienes from 1-Trimethylsilyl-2,3-butadienes and their Functionalizations
摘要:
Successive treatment of 1-trimethylsilyl-2,3-butadienes with iodine and tetra-n-butylammonium fluoride in the same flask affords 2-iodo-1,3-butadienes in good yields and their palladium-catalyzed carbonylation and alkynylation allows introduction of ester and alkynyl groups to the 2-position bearing an iodine atom leading to various 2,3-disubstituted 1,3-butadienes. (C) 1997 Elsevier Science Ltd. All rights reserved.
Palladium-catalyzed cross-coupling reaction of 2,3-diboryl1,3-butadiene with an alkenyl halide or a dienyl halide allowed us to straightforwardly prepare various kinds of acyclic cross-conjugatedpolyenes that are referred to as dendralenes. The present method is applicable to the synthesis of not only symmetrical [4]- and [6]dendralenes but also unsymmetrical [3]-to [5]dendralenes.
An efficient cross-coupling reaction using a low cost carbon-supported palladium (Pd/C) catalyst for the synthesis of cross-conjugated compounds, diaryl[n]dendralenes, has been developed. The reaction of a propargylic biscarbonate with phenylboronic acid using Pd/C and phosphine ligand (S-Phos) gave 2,3-diphenyl[2]dendralene in high yield. We found that Pd/C was an effective catalyst for the synthesis of dialyl[n]dendralenes. The synthesis of various dendralenes was successfully achieved under the optimized conditions, giving dialyl [2] and [4] dendralenes in good yields. (C) 2017 Elsevier Ltd. All rights reserved.
Preparation of 2-Iodo-1,3-butadienes from 1-Trimethylsilyl-2,3-butadienes and their Functionalizations
Successive treatment of 1-trimethylsilyl-2,3-butadienes with iodine and tetra-n-butylammonium fluoride in the same flask affords 2-iodo-1,3-butadienes in good yields and their palladium-catalyzed carbonylation and alkynylation allows introduction of ester and alkynyl groups to the 2-position bearing an iodine atom leading to various 2,3-disubstituted 1,3-butadienes. (C) 1997 Elsevier Science Ltd. All rights reserved.