Organocatalytic Regioselective Synthesis of Sulfur-Containing N-Alkyl Carbamates from Alkyne-Derived Cyclic Carbonates

Abstract

A highly regioselective synthesis of sulfur-containing N-alkyl carbamate from propargyl alcohol, carbon dioxide (CO 2) and amine via metal-free catalysis is described. The regioselective ring-opening addition of tri-substituted cyclic carbonate with amine was investigated in detail. A key feature of this system is the ability to afford tertiary β-hydroxyl N-alkyl carbamate with 100% selectivity by using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) as the catalyst in a wide range of reaction temperatures. The steric hindrance of amine and the use of ethanol favored the regioselective ring-opening addition reaction. A proposed mechanism for the ring-opening addition elaborated the underlying reason for the regioselective synthesis of sulfur-containing N-alkyl carbamate. This study provides a new alternative synthetic route to sulfur-containing N-alkyl carbamates from alkyne and CO 2 and may offer an attractive scaffold for further synthesis.

A Switchable Domino Process for the Construction of Novel CO2‐Sourced Sulfur‐Containing Building Blocks and Polymers

“…Poly(monothiocarbonate)s are attractive polymers for optic applications due to their high refractive index, but also for water purification due to the strong binding ability of sulfur atom to metals . Only one article reports the reaction of thiols with αCCs, and this only by UV‐activated thiol–ene addition to yield the trisubstituted ethylene carbonate 1 (Scheme , previous work) …”

“…After only 1min, the cyclic carbonate was fully converted into the expected b-oxothiocarbonate 2 as the main product (91 %), and the tetrasubstituted cyclic product 3 as the minor one (9 %) (Table 1, entry 1). With increasing reaction time, 2 progressively disappeared in favor of 3,s uggesting that 3 resulted from ar earrangement of 2.P roduct 3 was quantitatively recovered after 2h,and its structure was confirmed by 1 Ha nd 13 CN MR spectroscopy,H R-MS,a nd XRD of the recrystallized product (Scheme 2C;SISection 4.1, Table S8).…”

“…[8] Ther ing-opening of aCCs by thiols is potentially attractive to drastically enlarge the scope of these CO 2 -based synthons but is surprisingly unexplored. [13] In this work, we investigated the organocatalyzed thiolation of aCCs as an unprecedented source of alarge palette of novel sulfur-containing organic scaffolds and polymers.W e discovered that 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) catalyzed the quantitative ring-opening of aCCs by various thiols,yielding either the b-oxothiocarbonate 2 or the elusive tetrasubstituted ethylene carbonate 3 in high yield (Scheme 1). thiocarbonates) and polymer chemistries (e.g.p oly(monothiocarbonates)).…”

“…thiocarbonates) and polymer chemistries (e.g.p oly(monothiocarbonates)). [13] In this work, we investigated the organocatalyzed thiolation of aCCs as an unprecedented source of alarge palette of novel sulfur-containing organic scaffolds and polymers.W e discovered that 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) catalyzed the quantitative ring-opening of aCCs by various thiols,yielding either the b-oxothiocarbonate 2 or the elusive tetrasubstituted ethylene carbonate 3 in high yield (Scheme 1). [10] Poly(monothiocarbonate)s are attractive polymers for optic applications due to their high refractive index, [11] but also for water purification due to the strong binding ability of sulfur atom to metals.…”

“…[12] Only one article reports the reaction of thiols with aCCs,a nd this only by UV-activated thiol-ene addition to yield the trisubstituted ethylene carbonate 1 (Scheme 1, previous work). [13] In this work, we investigated the organocatalyzed thiolation of aCCs as an unprecedented source of alarge palette of novel sulfur-containing organic scaffolds and polymers.W e discovered that 1,8-diazabicyclo [5.4.0]undec-7-ene (DBU) catalyzed the quantitative ring-opening of aCCs by various thiols,yielding either the b-oxothiocarbonate 2 or the elusive tetrasubstituted ethylene carbonate 3 in high yield (Scheme 1). Product 2 was formed extremely rapidly at room temperature,w hereas 3 resulted from an ovel DBUcatalyzed reaction following an on/off switchable domino process.F inally,t he reactions were implemented for the synthesis of novel families of sulfur-containing polymers, including unprecedented polycyclics,with functionalities that were modulated by switching on/off the domino process.…”