Phosphinous chloride, diisopropyl

According to the latter approach, reducing sugars 128 were reacted with triethylammonium dimethyl boranophosphate in the presence of bis(2-oxo-3-oxazolidinyl)phosphinic chloride as condensing reagent, 3-nitro- 1,2,4-triazole as nucleophilic catalyst and A,A-diisopropyl-A-ethyl-amine to provide boranophosphate triester derivatives 129 as anomeric... 

Resin 23 was first swollen in CH2CI2 and, in a manner that parallels the route employed in the solution-phase synthesis, was reacted with a selected benzylsulfonyl chloride and t-BuOLi as a base to afford the corresponding sulfonamide resin 28, containing the first diversity element R. The sulfonamide resin 28 was then reacted under Mitsunobu conditions (PPha (triphenyl phosphine), DIAD (diisopropyl azodicarboxylate), THE, room temperature) with the appropriate alcohols. This process efficiently produced resin 29 and introduced the second diversity element R. Cyclization reaction of resin 29 was promoted by sodium hydride in DMF and led to the formation of the desired thiazolo[4,5-c] [l,2]thiazine resin 30. Treatment of resin 30 with mCPBA in CH2CI2 generated the resin-bound cyclic sulfonamide 31. Finally, the thiazolo[4,5-c][l,2]thiazine derivatives 5 were formed and cleaved from the resin (in a traceless manner" ) by treatment of resin 31 with the corresponding amines (R R" N diversity elements) in respectable yields (34 examples, from 11% to 29% for seven linear steps starting with Merrifield resin 1, Table 10.4). 

Dialkyl phosphines Diazoacetic ester Diazoamidobenzol Diazobenzene chloride Diethyl carbonate Diisopropyl higher alkyl ethers Ferrous perchlorate... 

Electron-rich and ortho-substituted aryl chlorides were converted to the respective anilines in excellent yields within 1 h on a 1 mmol scale, emphasizing the exceptional activation in combination with the electron-rich phosphine. Another class of strong a-donors are N-heterocychc carbenes. Their Pd(0) complexes can undergo facile oxidative addition of aryl halides. Nolan et al. [44] used the SIPr ligand (SIPr = (l,3-bis(2,6-diisopropyl)phenyl-4,5-dihydroimidazol-2-ylidene), 19) for the Pd-catalyzed arylation of stericaUy encumbered anilines with stericaUy demanding aryl chlorides at room temperature (Scheme 13.66). 

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