A concurrent process involving a gold N‐heterocyclic carbene (IPrAuNTf2) and an alcohol dehydrogenase is described for the first time. This cascade approach allows the development of a Meyer–Schuster rearrangement for the transformation of racemic propargylic alcohols, mostly with good selectivities towards the corresponding E‐allylic ketone intermediates, in aqueous medium, which are subsequently reduced to obtain the desired alcohol enantiomers with excellent optical purities.
Abstract
The combination of gold(I) and enzyme catalysis is used in a two‐step approach, including Meyer–Schuster rearrangement of a series of readily available propargylic alcohols followed by stereoselective bioreduction of the corresponding allylic ketone intermediates, to provide optically pure β,β‐disubstituted allylic alcohols. This cascade involves a gold N‐heterocyclic carbene and an enzyme, demonstrating the compatibility of both catalyst types in aqueous medium under mild reaction conditions. The combination of [1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene][bis(trifluoromethanesulfonyl)‐imide]gold(I) (IPrAuNTf2) and a selective alcohol dehydrogenase (ADH‐A from Rhodococcus ruber, KRED‐P1‐A12 or KRED‐P3‐G09) led to the synthesis of a series of optically active (E)‐4‐arylpent‐3‐en‐2‐ols in good yields (65–86 %). The approach was also extended to various 2‐hetarylpent‐3‐yn‐2‐ol, hexynol, and butynol derivatives. The use of alcohol dehydrogenases of opposite selectivity led to the production of both allyl alcohol enantiomers (93‐>99 % ee) for a broad panel of substrates.
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[SOLD] Cascade Designs Classic Zip Duffel, 40 LTR I've had this bag (and a twin) for quite a while and used it hard on multiple kayak trips in PNW and British Columbia, while living aboard for several years, a dozen car-camping forays, plus two cross-country (USA) moves. They both still look great and function perfectly. Absolutely bombproof! Amazing bags. 944g ea. retails at $160.00 ea.; asking $100.00 ea. + s/h + 3% =$0.30. images at https://imgur.com/a/NMbNjxZ
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[SOLD] Seattle Sports X-Large Waterproof Bags (Diameter: 12.5"; Height: 28") Another very rugged drybag. Two available. 644g ea. retail at $25.00 ea., asking $25.00 for the pair + s/h + 3% =$0.30. images at https://imgur.com/a/XTXZUwW
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[SOLD] Seattle Sports Small Waterproof Bags (Diameter: 7.5"; Height: 15") The workhorse on our kayak trips. They just do not show it (unlike myself). retail at $15.00 ea., asking $15.00/pair + s/h + 3% =$0.30. images at https://imgur.com/a/Nuq7MXa
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[SOLD] REI Small Waterproof Bags (Diameter: 7.5"; Height: 15") These two bags are indistinguishable from the small Seattle Sports bags above except for the logos. They likely came off the same production lines given their corporate locations and origin stories. They've also received the same treatment and delivered the same performance. Not coincidentally, I'm asking the same price! I haven't looked up REI's price but hey, it is REI. asking $15.00/pair + s/h + 3% =$0.30. images at https://imgur.com/a/aEddZgB
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[SOLD] SeaToSummit Ultra-Sil Compression Dry Sack, Size M (14 ltr.) Excellent condition as only used on one hike. retails at $47.00, asking $30.00 + s/h + 3% =$0.30. images at https://imgur.com/a/ZONLQ5I
I had purchased the Thermarest NeoAir Xtherm Max (https://www.thermarest.com/sleeping-pads/fast-and-light/neoair-xtherm-max-sleeping-pad/neoair-xtherm-max.html) a while back and have used it probably twenty or so times. I got it mainly because I can't sleep comfortably on foam pads and I roll around too much to use a mummy style mattress pad. I also do a lot of backpacking in the winter and have found the insulation to be great in very cold conditions especially for the weight of the mattress. My last backpacking trip I ended up getting an unusual rip on the side that I sleep on, too big to fix out on the field. I had called the warranty and repair department expecting to pay to get it fixed or at least have to send it in. I sent the picture of the tear and one look they told me they were sending me a replacement. I told them that I was in no hurry as there is still a lot of snow and mud here and obviosuly Covid is going around. But they had the replacement mattress sent out the day after our conversation. Very easy to deal with.
As someone who works in healthcare and is happy to get cheaper gear from Cascade, this is great.
Does anyone have experience with their pro program and what to expect?
Edit: All 3 codes sent!
I have a couple of Friends and Family 30% off codes for Cascade Designs ( MSR® | PackTowl® | Platypus® | SealLine® | Therm-a-Rest® ). They expire on 11 May, just leave a comment and Ill pick 3!
And what are standard rules to apply a cascade loops ?
I am returning a MSR HUBBA NX 1 due to a common delineation problem and the seam tape starting to peel. Anyhow, they asked me to send them pictures of the issues, I did, and they confirmed I qualified for the warranty.
This is my question. After I called to confirm they received the pictures of my issues, the representative asked me to cut up my tent and send a picture of it to make sure no one will reattempt to claim the warranty with the same tent. Only then they will send out my new tent body. Is this normal practice? I’m just hesitant to cut up a $300+ tent.
Let me know and thanks for any feedback!
Edit: Thank you for the confirmations. It has been cut up and I managed to only get a few of my tears on it.
Trying to build a robot lift a pretty light load repeatedly in a small span of time.
Which design is more suitable for the job?
Hi all,
I recently gained access to the cascade designs pro deals. I have been camping and hiking my entire life but use mostly middle ground gear because it's cost effective. The pro deals give me the price that stores buy at or better. Given all of the brands under cascade designs, what would your list consist of and why (assume I have nothing)?
The combination of gold(I) and enzyme catalysis has been exhaustively analysed aiming to develop a two‐step concurrent approach. This strategy consists of a Meyer‐Schuster rearrangement of a series of easily available propargylic alcohols followed by the stereoselective bioreduction of the corresponding allylic ketone intermediates, providing optically pure β,β‐disubstituted allylic alcohols. Thus, the first concurrent cascade example involving the use of a gold N‐heterocyclic carbene and an enzyme is described, demonstrating the compatibility of both catalyst types in aqueous medium under very mild conditions. The combination of [1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene][bis(trifluoromethanesulfonyl)‐imide]gold(I) (IPrAuNTf 2 ) and a selective alcohol dehydrogenase (ADH‐A from Rhodococcus ruber , KRED‐P1‐A12 or KRED‐P3‐G09), has allowed the synthesis of a series of optically active ( E )‐4‐arylpent‐3‐en‐2‐ols in good isolated yields (65‐86%). The chemoenzymatic approach was also successfully extended to various 2‐hetarylpent‐3‐yn‐2‐ol, hexynol and butynol derivatives. Remarkably, the use of alcohol dehydrogenases of opposite selectivity has allowed the straightforward production of both allyl alcohol enantiomers (93‐>99% ee ) for a broad panel of substrates bearing different substitutions in the aromatic ring.
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