Diisopinocampheylboron triflate

Achiral ketones, for example, 3-pentanone, can be converted predominantly into (Z)-boron enolates [(Z)/( )>97 3] by treatment with (- )-diisopinocampheylboron triflate. Subsequent addition to aldehydes, followed by an oxidative workup procedure, delivers /i-hydroxy ketones with a diastcrcomeric ratio of 95 5 to 98 2 (synjanli) and the xpn-products with 66 to 93% ee33. 

Enantioselectivity can also be induced by use of chiral boron enolates. Both the (+) and (-) enantiomers of diisopinocampheylboron triflate have been used to generate syn addition through a cyclic TS.132 The enantioselectivity was greater than 80% for most cases that were examined. Z-Boron enolates are formed under these conditions and the products are 2,3-syn. 

Alternate Name diisopinocampheylboron triflate Ipc2BOTf. Physical Data colorless, viscous oil bp <150°C/0.01 mmHg ( bulb-to-bulb distillation ) (—)Ipc2BOTf [ctJo —43.5° (c = 30.4, hexane) "B NMR (hexane) broad singlet at 5 = 60 ppm (with reference to BF3 OEt2). 

Paterson developed asymmetric enolboration-aldolization involving diisopinocampheylboron triflate (57, 32), He has shown the utility of enolboration for the synthesis of various macrolide molecules. His recently completed target molecules include Concanamycin F (33) and the potential anticancer agent, Discodermolide (34) (Figure 6). 

---

See also in sourсe #XX -- [ ]

---