P‐OR Functional Phosphanido and/or Li/OR Phosphinidenoid Complexes?

Abstract

Keywords: Phosphanes / P ligands / Lithium / Phosphinidenoids / Tungsten / Structure elucidation P-H,P-OR-substituted phosphane complexes 3a-e have been synthesized by two methods: (1) the thermal reaction of 2Hazaphosphirene complex 1 with methanol, n-butanol, or ethylene glycol monomethyl ether (3b,c,e) or (2) the reaction of P-chlorophosphane complex 2 with appropriate sodium phenolate salts (3a,d). All the complexes 3a-e were obtained in good yields and fully characterized by NMR, IR, MS, and elemental analysis. Furthermore, the structures of 3a, 3d and 3e were confirmed unambiguously by X-ray analysis. The de-

Recent Progress in Organocatalytic Asymmetric Domino Transformations

“…[263] Li andc o-workersa lso reported the synthesis of enantioenricheds piro-1,3-indandiones 681 by using a domino Michael/aldol reaction between 308 and g-nitroaldehydes 682 (Scheme 178). [264] Theq uinidine-derived squaramide 634 was used as the catalyst, which producedt he desired products 681 in good yields, good to high ee values, ande xcellent diastereoselectivities. [264] Using the same substrates 308,t hese authors later developed ad omino sulfa-Michael/Michael reactionw ith tert-butyl4 -mercapto-2-butenoate (626b)f or the asymmetric synthesis of the enantioenriched spiro[indane-1,3-dione tetrahydrothiophene] frameworks 683 using the cyclohexanediamine-derived thiourea 581 as the organocatalyst (Scheme 178).…”

“…[264] Theq uinidine-derived squaramide 634 was used as the catalyst, which producedt he desired products 681 in good yields, good to high ee values, ande xcellent diastereoselectivities. [264] Using the same substrates 308,t hese authors later developed ad omino sulfa-Michael/Michael reactionw ith tert-butyl4 -mercapto-2-butenoate (626b)f or the asymmetric synthesis of the enantioenriched spiro[indane-1,3-dione tetrahydrothiophene] frameworks 683 using the cyclohexanediamine-derived thiourea 581 as the organocatalyst (Scheme 178). [265] Chen andc o-workersl ater developed at hree-componentd omino Knoevenagel/Michael/aldol/aldol condensation reactiono fa ldehydes 2,i ndane-1,3-dione (684)a nd prochiral 4-substituted cyclohexanones 685.…”

Organocatalytic Asymmetric Synthesis of Tetrahydrothiophenes and Tetrahydrothiopyrans

“…In the next year, Li and co-workers developed a double Michael reaction sequence between 2-arylideneindane-1,3-diones 59 and 4-mercaptobut-2-enoate 29b for the construction of chiral spiro[indane-1,3-dione-tetrahydrothiophenes] 60 in the presence of bifunctional thiourea catalyst 61 (Scheme 21). [36] As shown in Scheme 21, the desired spiro products 60 were isolated in good yields and with high enantioselectivities. In the first step of the cascade reaction sequence, both reactants are synergistically activated by the bifunctional chiral thioureaamine catalyst: the 2-arylideneindane-1,3-dione is activated by thiourea through hydrogen bonding, and tert-butyl 4mercaptobut-2-enoate is activated by the tertiary amine.…”

1,4‐Dithiane‐2,5‐diol: An Attractive Platform for the Synthesis of Sulfur‐Containing Functionalized Heterocycles

“…[22] The development of methods for the stereoselective construction of chiral spirocyclic tetrahydrothiophene derivatives has become a topical subject in synthetic chemistry. A variety of spirotetrahydrothiophene scaffolds anchored to different skeletons have been described in a flurry of papers appearing in the literature over the last four years, [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] taking advantage of the excellent anellating properties both of 1 and of the derived 4-mercaptobut-2-enoates 11a-d in partnership with α,unsaturated carbonyl compounds. These transformations have been reviewed very recently, highlighting the pivotal role of organocatalysis as a powerful and versatile tool for the rapid construction of spirotetrahydrothiophene motifs.…”

“…[38] A similar strategy was applied to prepare chiral spiro[indane-1,3-dione-tetrahydrothiophene] skeletons 52, which were constructed in good yields (75-99 %) and with high enantioselectivities (89-99 % ee) and diastereoselectivities by treating 2-arylideneindane-1,3-diones and 4mercaptobut-2-enoate 11c in the presence of a tertiary aminethiourea organocatalyst. [39]…”