**Recent Advances in Metal-Catalyzed Alkyl–Boron (C(sp<sup>3</sup> ))–C(sp<sup>2</sup> )) Suzuki-Miyaura Cross-Couplings**

#### **Janwa El-Maiss 1,**† **, Tharwat Mohy El Dine 2,**† **, Chung-Shin Lu <sup>3</sup> , Iyad Karamé 4 , Ali Kanj <sup>4</sup> , Kyriaki Polychronopoulou 5,6,\* and Janah Shaya 7,8,\***


Received: 25 January 2020; Accepted: 19 February 2020; Published: 5 March 2020

**Abstract:** Boron chemistry has evolved to become one of the most diverse and applied fields in organic synthesis and catalysis. Various valuable reactions such as hydroborylations and Suzuki–Miyaura cross-couplings (SMCs) are now considered as indispensable methods in the synthetic toolbox of researchers in academia and industry. The development of novel sterically- and electronically-demanding C(sp<sup>3</sup> )–Boron reagents and their subsequent metal-catalyzed cross-couplings attracts strong attention and serves in turn to expedite the wheel of innovative applications of otherwise challenging organic adducts in different fields. This review describes the significant progress in the utilization of classical and novel C(sp<sup>3</sup> )–B reagents (9-BBN and 9-MeO-9-BBN, trifluoroboronates, alkylboranes, alkylboronic acids, MIDA, etc.) as coupling partners in challenging metal-catalyzed C(sp<sup>3</sup> )–C(sp<sup>2</sup> ) cross-coupling reactions, such as B-alkyl SMCs after 2001.

**Keywords:** Suzuki–Miyaura cross-couplings; C(sp<sup>3</sup> ) –C(sp<sup>2</sup> ); alkylboron reagents; metal catalysis
