One-Pot Synthesis of Less Accessible N-Boc-Propargylic Amines through BF₃-Catalyzed Alkynylation and Allylation Using Boronic Esters

Abstract

An efficient synthesis of α-alkynylor α-allyl-substituted N-Boc-propargylic amines is described via an alkynylation or allylation of alkynyl-substituted N-Boc-imines. Our strategy relies on the BF 3 -mediated in situ generation of alkynyl imines followed by alkynylation or allylation with the corresponding boronic esters. A range of less accessible N-Bocpropargylic amines were obtained in moderate to good yields under mild and acidic conditions with higher atom economy compared to the previous methods.

Silica-Based Aerogels with Tunable Properties: The Highly Efficient BF3-Catalyzed Preparation and Look inside Their Structure

“…These facts have a decisive effect not only on the properties of the final material, aerogel, but also on the possibility of obtaining it as a solid (monolithic), homogeneous, and high-quality material. This catalyst, i.e., BF 3 ·Et 2 O, is an efficient LA that is widely used in various organic reactions. − There are mentions in the literature about the BF 3 catalysts’ usage to obtain hybrid organic–inorganic materials (via the epoxide ring opening) and epoxy-silica aerogels by nonaqueous sol–gel process. − However, to the best of our knowledge, this is the first example of a highly efficient BF 3 -catalyzed sol–gel process of alkoxysilanes to produce SAs by an aqueous sol–gel process.…”

Metal-free multicomponent approach for the synthesis of propargylamine: a review

“…Yasumoto et al 42 applied organoborane compounds as nucleophile e.g. alkynyl or allyl boronate (72, 73) used for the synthesis of α-alkynyl and α-allyl substituted N -Boc (Boc = tertiary butyloxy carbonyl) propargylamine via alkynylation and allylation of alkynyl substituted N -Boc imines (74–76).…”

“…27 There are only a few reports published in the literature describing the A3 and other MCR (multicomponent reaction) for the metal-free propargylamine synthesis. [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] From the green and sustainable point of view, metal-free synthesis is the best eco-friendly approach while assessing environmental safety. The object of green chemistry mainly focuses on the development of novel methodologies and alternative sustainable synthetic strategies, which must include the environmental considerations.…”

N,N‐Diacylaminals as Emerging Tools in Synthesis: From Peptidomimetics to Asymmetric Catalysis

“…The iminep recursor could also be generated in situ and employed to produce ak ey intermediate in the synthesis of (+ +)-cylindradine B. [41] Althought hese asymmetricr eactions involve generation of N-Boc imines from N-Boc aminals under acid conditions, [42] their generationu nder basic conditions is another promising possibility.I nt his case, acid-sensitive( pro)nucleophiles can be employed, thus broadening the syntheticu tility of N,N-diacylaminals. The approachi sq uite simple and consists of the previous installation of an additional Boc group into the aminal moiety as disclosed by Maruoka and co-workersinahighly stereoselectivep hase transfer catalyzed Mannich reactiono fg lycine derived aldimines [43] (Scheme 12).…”